ELYMUS L.

Mary E. Barkworth

Julian J.N. Campbell

Bjorn Salomon

Plants perennial; sometimes cespitose, with or without rhizomes, sometimes stoloniferous. Culms 8–180(220) cm, usually erect to ascending, sometimes strongly decumbent to prostrate, usually glabrous. Leaves usually evenly distributed, sometimes somewhat basally concentrated; sheaths open for most of their length; auricles often present; ligules membranous, truncate or rounded, sometimes acute, entire or erose, often ciliolate; blades 1–24(25) mm wide, abaxial surfaces usually smooth or scabrous, sometimes with hairs, adaxial surfaces scabrous or with hairs, particularly over the veins, usually with unequal, not strongly ribbed, widely spaced veins, sometimes with equal, strongly ribbed, closely spaced veins. Inflorescences spikes, usually exserted, with 1–3(5) spikelets per node, internodes (1.5)2–26 mm; rachises with scabridulous, scabrous, or ciliate edges. Spikelets usually appressed to ascending, sometimes strongly divergent or patent, with 1–11 florets, the distal florets often reduced, the lowest florets usually functional, sterile and glumelike in some species; disarticulation usually above the glumes and beneath each floret, sometimes also below the glumes or in the rachises. Glumes usually 2, absent or highly reduced in some species, usually equal to subequal, sometimes unequal, usually linear-lanceolate to linear, setaceous, or subulate, sometimes oblanceolate to obovate, (0)1–7-veined, sometimes keeled over 1 vein, not necessarily the central vein, the keel vein sometimes extended into an awn; lemmas linear-lanceolate, obscurely 5(7)-veined, apices acute, often awned, sometimes bidentate, teeth to 0.2 mm, sometimes with bristles, bristles to 10 mm, awns terminal or from the sinus, straight or arcuately divergent, not geniculate; paleas from shorter than to slightly longer than the lemmas, keels scabrous or ciliate, at least in part; anthers 3, 0.7–7 mm. Caryopses with hairy apices. x = 7. Haplomes St, H, Y, P. Name from the Greek elyo, ‘rolled up’, the caryopses being tightly embraced by the lemma and palea.

As interpreted here, Elymus is a widespread, north-temperate genus of about 150 species. It includes Sitanion Raf.  and Roegneria K. Koch, but moves some taxa that others include in Elymus to Leymus , Pascopyrum , Pseudoroegneria, and Thinopyrum. [Recently (Barkworth 2009), I agreed with Yen et al. in adopting a narrower interpretation of the genus. That would move Elymus ciliaris to Roegneria ciliaris and and , in which Roegneria and Thirty-two species of Elymus are native to the Flora region. Of the seven non-native species treated, one is established (E. repens ), two are distributed as forage (E. dahuricus  and E. hoffmannii ), two are known from ballast dumps and are not established (E. tsukushiensis  and E. ciliaris ), and two (E. caninus  and E. semicostatus ) have been attributed to the Flora region but specimens documenting the reports have not been located. Eight named, naturally occurring, intrageneric hybrids are described at the end of the treatment. They are not included in the key. As mentioned in the descriptions of the non-hybrid species, other interspecific hybrids undoubtedly exist. Because many of the hybrids are partially fertile, backcrossing and introgression occurs. Intergeneric hybrids are treated under ΧElyhordeum, ΧElyleymus , ΧPascoleymus, ΧPseudelymus , and ΧTriticosecale; most are sterile.

The complex patterns of morphological diversity within Elymus in North America probably reflect a combination of multiple origins involving different progenitors, introgression, hybridization both within the genus and with other members of the tribe, and morphological plasticity. Little is known concerning the relative importance of these factors. Two infraspecific ranks have been used to aid in circumscribing the known variation. In general, infraspecies taxa that show great morphological and ecological distinction are treated as subspecies; others, as varieties.

All species of Elymus are alloploids that combine one copy of the St haplome present in Pseudoroegneria with at least one other haplome. So far as is known, all species that are native to North America, as well as many species native to northern Eurasia, are tetraploids with one additional haplome, the H genome from Hordeum sect. Critesion . Many Asian species combine the St haplome with the Y haplome, for which there are no known diploids; such species are sometimes placed in the segregate genus Roegneria. This treatment includes two such species, E. ciliaris and E. semicostatus. In addition, the treatment includes two hexaploid species, E. tsukushiensis and E. dahuricus, that combines all three haplomes. Elymus repens and E. hoffmannii, the other two hexaploid species in this treatment, basically combine two copies of the St haplome with one of the H haplome, but the molecular data for E. repens point to a more complex situation (Mason-Gamer 2001). For further discussion of generic delimitation in the Triticeae, see Barkworth (2000), Yen et al. (2005), and Barkworth and von Bothmer (2005).

Elymus is sometimes divided into multiple sections (see, for example, Tsvelev 1976; Lφve 1984). There are, however, no detailed morphological descriptions of the sections, making it difficult to determine how to treat the North American species. It is notable that the species with solitary spikelets are concentrated in western and northern North America, whereas the species with multiple spikelets at a node are most prevalent east of the Rocky Mountains, from southern Canada to the Gulf Coast. There are exceptions to this statement. For instance, species with multiple spikelets and disarticulating rachises are primarily western in their distribution, and E. glaucus , a species with multiple spikelets and non-disarticulating rachises, is western. Like the western species with solitary spikelets, and unlike most eastern species, its glumes have a hyaline margin.

In the key and descriptions, unless otherwise stated, the following conventions are observed: the number of culm nodes refers to the number of nodes above the base; measurements of spikes include the awns, while measurements of spikelets, glumes, and lemmas do not; rachis internodes are measured in the middle of the spike; glume widths of lanceolate to linear glumes are measured at the widest point, and those of linear to setaceous glumes about 5 mm above the base of the glumes; the number of florets in a spikelet includes the distal reduced, sterile florets; and dates of anthesis, when provided, are for the central range of each species.

The curvature of the lemma awns is often important in identifying individual species. The curvature increases with maturity, and may vary within a spike. If a plant appears to have at least some strongly curved lemma awns, it should be taken through the “strongly curved” side of the key.

SELECTED REFERENCES Barkworth, M.E. 1997. Taxonomic and nomenclatural comments on the Triticeae in North America. Phytologia 83:302–311; Barkworth, M.E. 2000. Changing perceptions in the Triticeae. Pp. 110–120 inS.W.L. Jacobs and J. Everett (eds.). Grasses: Systematics and Evolution. CSIRO Publishing, Collingwood, Victoria, Australia . 408 pp.; Barkworth, M.E. and R. von Bothmer. 2005. Twenty-one years later: Lφve and Dewey’s genomic classification proposal. Czech J. Genet. Pl. Breed. 41:3–9; Bennett, B.A. 2006. Siberian Wild Rye (Elymus sibiricus L., Poaceae) in western North America: Native or introduced? BEN [Botanical Electronic News] #366. http://www.ou.edu/cas/botany-micro/ben/; Bφdvarsdσttir, S.K. and K. Anamthawat-Jonsson. 2003. Isolation, characterization, and analysis of Leymus-specific DNA sequences. Genome 46:673–682; Bowden, W.M. 1958. Natural and artificial ΧElymordeum hybrids. Canad. J. Bot. 36:101–123; Bowden, W.M. 1964. 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Sci. 62:19–38; Campbell, J.J.N. and A. Haines. 2002. Corrections and additions to: “Campbell, J.J.N. 2000. Notes on North American Elymus species (Poaceae) with paired spikelets: I. E. macgregorii sp. nov. and E. glaucus ssp. mackenzii comb. nov. J. Ky. Acad. Sci. 61:88–98.” J. Kentucky Acad. Sci. 62:65; Church, G.L. 1954. Interspecific hybridization in eastern Elymus. Rhodora 56:185–197; Church, G.L. 1958. Artificial hybrids of Elymus virginicus with E. canadensis, E. interruptus, E. riparius, and E. wiegandii. Amer. J. Bot. 45:410–417; Church, G.L. 1967a. Taxonomic and genetic relationships of eastern North American species of Elymus with setaceous glumes. Rhodora 69:121–162; Church, G.L. 1967b. Pine Hills Elymus. Rhodora 69:330–345; Davies, R.S. 1980. Introgression between Elymus canadensis and E. virginicus L. (Triticeae, Poaceae) in south central United States . Ph.D. dissertation, Texas A&M University, College Station, Texas, U.S.A. 232 pp.; Dewey, D.R. 1963. Natural hybrids of Agropyron trachycaulum and Agropyron scribneri. Bull. Torrey Bot. Club 90:111–120; Dewey, D.R. 1965. Morphology, cytology, and fertility of synthetic hybrids of Agropyron spicatum Χ Agropyron dasystachyum–riparium. Bot. Gaz. 126:269–275; Dewey, D.R. 1967a. Genome relations between Agropyron scribneri and Sitanion hystrix. Bull. Torrey Bot. Club 94:395–404; Dewey, D.R. 1967b. Synthetic Agropyron–Elymus hybrids: II. Elymus canadensis Χ Agropyron dasystachum. Amer. J. Bot. 54:1084–1089; Dewey, D.R. 1968. Synthetic hybrids of Agropyron dasystachyum Χ Elymus glaucus and Sitanion hystrix. Bot. Gaz. 129:316–322; Dewey, D.R. 1970. The origin of Agropyron albicans. Amer. J. Bot. 57:12–18; Dewey, D.R. 1974. Cytogenetics of Elymus sibiricus and its hybrids with Agropyron tauri, Elymus canadensis, and Agropyron caninum. Bot. Gaz. 135:80–87; Dewey, D.R. 1975. Introgression between Agropyron dasystachyum and A. trachycaulum. Bot. Gaz. 136:122–128; Dewey, D.R. 1976. Cytogenetics of Agropyron pringlei and its hybrids with A. spicatum, A. scribneri, A. violaceum, and A. dasystachum. Bot. Gaz. 137:179–185; Dewey, D.R. 1982. Genomic and phylogenetic relationships among North American perennial Triticeae. Pp. 51–58 in J.R. Estes, R.J. Tyrl, and J.N. Brunken (eds.). Grasses and Grasslands. University of Oklahoma Press, Norman, Oklahoma, U.S.A. 312 pp.; Gabel, M.L. 1984. A biosystematic study of the genus Elymus (Gramineae: Triticeae). Proc. Iowa Acad. Sci. 91:140–146; Gillett, J.M. and H.A. Senn. 1960. Cytotaxonomy and infraspecific variation of Agropyron smithii Rydb. Canad. J. Bot. 38:747–760; Gillett, J.M. and H.A. Senn. 1961. A new species of Agropyron from the Great Lakes. Canad. J. Bot. 39:1169–1175; Godley, E.J. 1947. The variation and cytology of the British species of Agropyron and their natural hybrids. Master’s thesis, Trinity College, Cambridge, England . 152 pp.; Hitchcock, A.S. 1935. Manual of the Grasses of the United States . U.S. Government Printing Office, Washington, D.C., U.S.A. 1040 pp.; Hitchcock, A.S. 1951. Manual of the Grasses of the United States , ed. 2, rev. A. Chase. U.S.D.A. Miscellaneous Publication No. 200. U.S. Government Printing Office, Washington, D.C., U.S.A. 1051 pp.; Hitchcock, C.L., A. Cronquist, and M. Ownbey. 1969. Vascular Plants of the Pacific Northwest, Vol. 1: Vascular Cryptogams, Gymnosperms, and Monocotyledons. University of Washington Press, Seattle, Washington, U.S.A. 914 pp.; Hultιn, E. 1968. Flora of Alaska and Neighboring Territories. Stanford University Press, Stanford, California, U.S.A. 1008 pp.; Jensen, K.B. 1993. Elymus magellanicus and its intra- and inter-generic hybrids with Pseudoroegneria spicata, Hordeum violaceum, E. trachycaulus, E. lanceolatus, and E. glacus (Poaceae: Triticeae). Genome 36:72–76; Jensen, K.B. and K.H. Asay. Cytology and morphology of Elymus hoffmanni (Poaceae: Triticeae): A new species from the Erzurum Province of Turkey. Int. J. Pl. Sci. 157:750–758; Jones, S.B., Jr. and N.C. Coile. 1988. The Distribution of the Vascular Flora of Georgia . University of Georgia, Athens, Georgia , U.S.A. 230 pp.; Jozwik, F.X. 1966. A biosystematic analysis of the slender wheatgrass complex. Ph.D. dissertation, University of Wyoming, Laramie, Wyoming, U.S.A. 112 pp.; Lepage, E. 1952. Ιtudes sur quelques plantes amιricaines: II. Hybrides intergιnιriques; Agrohordeum et Agroelymus. Naturaliste Canad. 79:241–266; Lepage, E. 1965. Revision gιnιalogique de quelques ΧAgroelymus. Naturalise Canad. 92:205–216; Mason-Gamer, R.J. 2001. Origin of North American Elymus (Poaceae:Triticeae) allotetraploids based on granule-bound starch synthase gene sequences. Syst. Bot. 26:757–768; Nelson, E.N. and R.J. Tyrl. 1978. Hybridization and introgression between Elymus canadensis and Elymus virginicus. Proc. Oklahoma Acad. Sci. 58:32–34; Pohl, R.W. 1959. Morphology and cytology of some hybrids between Elymus canadensis and E. virginicus. Proc. Iowa Acad. Sci. 66:155–159; Pohl, R.W. 1966. ΧElyhordeum iowense, a new intergeneric hybrid in the Triticeae. Brittonia 18:250–255; Porsild, A.E. and W.J. Cody. 1980. Vascular Plants of the Continental Northwest Territories, Canada . National Museum of Natural Sciences, National Museums of Canada , Ottawa, Ontario, Canada . 667 pp.; Pyrah, G.L. 1983. Agropyron arizonicum (Gramineae: Triticeae) and a natural hybrid from Arizona. Great Basin Naturalist 43: 131–135; Salomon, B., R. von Bothmer, and N. Jacobsen. 1991. Intergeneric crosses between Hordeum and North American Elymus (Poaceae: Triticeae). Hereditas 114:117–122; Sanders, T.S., J.L. Hamrick, and L.R. Holden. 1979. Allozyme variation in Elymus canadensis from the tallgrass prairie region: Geographic variation. Amer. Midl. Naturalist 101:1–12; Smith, E.B. (ed.). 1991. An Atlas and Annotated List of the Vascular Plants of Arkansas, ed. 2. Edwin B. Smith, Fayetteville, Arkansas, U.S.A. 489 pp.; Snyder, L.A. 1950. Morphological variability and hybrid development in Elymus glaucus. Amer. J. Bot. 37:628–636; Snyder, L.A. 1951. Cytology of inter-strain hybrids and the probable origin of variability in Elymus glaucus. Amer. J. Bot. 38:195–202; Stebbins, G.L., Jr. 1957. The hybrid origin of microspecies in the Elymus glaucus complex. Pp. 336–340 in International Union of Biological Sciences (eds.). Proceedings of the International Genetics Symposia, 1956: Tokyo & Kyoto, September 1956. Organizing Committee, International Genetics Symposia, Science Council of Japan, Tokyo, Japan. 680 pp.; Stebbins, G.L., Jr. and L.A. Snyder. 1956. Artificial and natural hybrids in the Gramineae, tribe Hordeae: IX. Hybrids between the western and eastern species. Amer. J. Bot. 43:305–312; Steyermark, J.A. 1963. Flora of Missouri. Iowa State University Press, Ames, Iowa, U.S.A. 1725 pp.;; Sun, G.-L. and B. Salomon. 2003. Microsatellite variability and heterozygote deficiency in the arctic-alpine Alaskan wheatgrass (Elymus alaskanus) complex. Genome 46:729–737; Sun, G.-L., B. Salomon, and R. von Bothmer. 1998. Characterization of microsatellite loci from Elymus alaskanus and length polymorphism in several Elymus species (Triticeae: Poaceae). Genome 41:455–463; Sun, G.L., H. Tang, and B. Salomon. 2006. Molecular diversity and relationships of North American Elymus trachycaulus and the Eurasian E. caninus species. Genetica 127:55–64; Svitashev, S., T. Bryngelsson, X. Li, and R.R.-C. Wang. 1998. Genome-specific repetitive DNA and RAPD markers for genome identification in Elymus and Hordelymus. Genome 41:120–128; Tsvelev, N.N. 1976. Zlaki SSSR [Grasses of the U.S.S.R.]. Nauka, Leningrad [ St. Petersburg], Russia . 788 pp.; Vilkomerson, H. 1950. The unusual meiotic behavior of Elymus wiegandii. Exp. Cell Res. 1:534–542; Wilson, B.L., J. Kitzmiller, W. Rolle, and V.D. Hipkins. 2001. 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1. Spikelets 1 at all or most nodes; glumes with flat, non-indurate bases, glume bodies linear-lanceolate to obovate, margins hyaline, scarious, or chartaceous; lemmas awned or unawned 2.

2. Anthers 3–7 mm long; plants often strongly rhizomatous, sometimes not or only weakly rhizomatous 3

3. At least some lemmas with strongly divergent, outcurving, or recurved awns 4

3. Lemmas unawned or with straight to flexuous awns 7

4. Culms prostrate to decumbent and geniculate, 20–50 cm tall; plants of subalpine and alpine habitats 32. E. sierrae (in part)

4. Culms erect or decumbent only at the base, (15)40–130 cm tall; plants of valley and montane, but not subalpine or alpine, habitats 5

5. Plants strongly rhizomatous; blades 1–3 mm wide 34. E. albicans

5. Plants cespitose or weakly rhizomatous; blades 1.5–6 mm wide 6

6. Spikes often drooping to pendent at maturity; rachis internodes 11–17 mm long; plants of the southwestern United States 29. E. arizonicus

6. Spikes erect to slightly nodding at maturity; rachis internodes 5–12 mm long; plants of the northwestern contiguous United States 33. E. wawawaiensis

7. Lemmas 12–14 mm long; plants not or weakly rhizomatous 8

7. Lemmas 7–12 mm long; plants not, weakly, or strongly rhizomatous 9

8. Palea keels straight or slightly outwardly curved below the apices, apices about 0.2 mm wide between the vein ends E. glaucus (in part)

8. Palea keels distinctly outwardly curved below the apices; apices 0.3–0.7 mm wide between the vein ends 39. E. semicostatus

9. Glumes keeled distally, keels smooth and inconspicuous proximally, scabrous and conspicuous distally; lemmas glabrous 10

9. Glumes not keeled or keeled throughout their length, keels smooth or scabrous throughout, sometimes hairy, conspicuous or not 11

10.  Adaxial surfaces of the blades usually sparsely pilose, sometimes glabrous, veins smooth, the primary veins separated by secondary veins; plants strongly rhizomatous.. 35. E. repens

10.  Adaxial surfaces of the blades glabrous, veins smooth or scabrous, all veins more or less equally prominent; plants slightly to moderately rhizomatous................. 36. E. hoffmannii

11.  Plants strongly rhizomatous; glumes 5–9 mm long; lemmas densely to sparsely hairy or glabrous 27. E. lanceolatus (in part)

11.  Plants cespitose or weakly rhizomatous; glumes 6–19 mm long; lemmas glabrous or pubescent, never densely hairy 12

12.  Spikelets usually at least twice as long as the internodes; internodes 4–12 mm long; glumes often awned, sometimes unawned; blades usually lax.... 10. E. glaucus (in part)

12.  Spikelets from shorter than to almost twice as long as the internodes; internodes 9–27 mm long; glumes unawned; blades usually straight 28. E. stebbinsii

2. Anthers 0.7–3 mm long; plants usually not or weakly rhizomatous, sometimes strongly rhizomatous.

13.  Culms prostrate or strongly decumbent at the base; disarticulation in the rachises or beneath the florets; plants of subalpine, alpine, and arctic habitats.

14.  Glumes unawned or with awns to 1 mm long; plants of arctic regions. 26. E. alaskanus (in part)

14.  Glumes awned, awns 3–30 mm long; plants of subalpine and alpine regions.

15.  Anthers 1–1.6 mm long; internodes 2.5–5(7) mm long; disarticulation initially in the rachises; spikelets appressed to ascending................................................. 31. E. scribneri

15.  Anthers 2–3.5 mm long; internodes 5–15 mm long; rachises not disarticulating; spikelets ascending to divergent.................................................................. 32. E. sierrae (in part)

13.  Culms usually ascending to erect, sometimes geniculate or weakly decumbent at the base; disarticulation beneath the florets; plants of sea level to subalpine habitats 16

16.  Lemmas with coarse, stiff, marginal hairs up to 1 mm long; paleas 2/3–4/5 as long as the lemmas, with wide, rounded apices.................................................................. 38. E. ciliaris

16.  Lemmas with the marginal hairs, if present, similar to those elsewhere on the lemma; paleas 3/4 as long as to slightly longer than the lemmas, tapering to the apices 17

17.  Lemmas awned, awns 7–40 mm long.

18.  Lemma awns strongly arcuate to outcurving or recurved.

19.  Spikes 8–12 cm long, straight, erect or inclined; blades 2–4 mm wide 30. E. bakeri

19.  Spikes 7–30 cm long, flexuous, nodding to pendent; blades 5–14 mm wide... 13. E. sibiricus (in part)

18.  Lemma awns usually straight or flexuous, or, if shorter than 10 mm, sometimes weakly curving.

20.  Glumes with hairs on the adaxial (inner) surface, these often inconspicuous... 23. E. caninus

20.  Glumes glabrous on the adaxial (inner) surface.

21.  Palea keels distinctly outwardly curved below the apices, winged, not or scarcely extending beyond the intercostal region; apices 0.3–0.5 mm wide.. 37. E. tsukushiensis

21.  Palea keels straight or slightly outwardly curved below the apices, not winged, often extending beyond the intercostal region, sometimes forming teeth; apices 0.1–0.3 mm wide.

22.  Glumes 1.8–2.3 mm wide, margins 0.2–0.3 mm wide.. 22. E. trachycaulus (in part)

22.  Glumes 0.4–1.5(2) mm wide, margins 0.1–0.2 mm wide.

23.  Spikes erect or almost so, 0.5–2 cm wide......... 10.E. glaucus (in part)

23.  Spikes nodding to pendent, 2–5 cm wide........ 13. E. sibiricus (in part)

17.  Lemmas unawned or with awns up to 7 mm long.

24.  Plants strongly rhizomatous.............................................. 27. E. lanceolatus (in part)

24.  Plants not or only shortly rhizomatous.

25.  Glumes 1/3–2/3 as long as the adjacent lemmas.

26.  Glumes 0.8–1.8 mm wide, lanceolate, margins subequal; lemmas evenly hairy or glabrous distally........................................................... 25. E. macrourus

26.  Glumes 1.5–2 mm wide, oblanceolate to obovate, margins unequal; lemmas glabrous, evenly hairy, or more densely hairy distally 26. E. alaskanus (in part)

25.  Glumes 3/4 as long as to slightly longer than the adjacent lemmas.

27.  Glumes 3(5)-veined; glume margins unequal, the wider margins 0.3–1 mm wide, usually widest in the distal 1/3; lemma awns 0.5–3 mm long........ 24. E. violaceus

27.  Glumes 3–7-veined, glume margins equal, 0.1–0.5 mm wide, widest at or slightly beyond midlength; lemmas unawned or with awns to 40 mm long.

28.  Glumes 1.8–2.3 mm wide, margins 0.2–0.3 mm wide.. 22. E. trachycaulus (in part)

28.  Glumes 0.4–1.5(2) mm wide, margins 0.1–0.2 mm wide. 10. E. glaucus (in part)

1. Spikelets 2–3(5) at all or most nodes; glumes often with subterete to terete, indurate bases, sometimes with flat, non-indurate bases, glume bodies linear-lanceolate to setaceous or subulate, margins usually firm, sometimes hyaline or scarious; lemmas usually awned, awns up to 120 mm long.

29.  Rachises disarticulating at maturity; glumes 10–135 mm long including the awns, sometimes split longitudinally, flexuous to outcurving from near the base; lowest floret in each spikelet sometimes sterile; blades 1–6 mm wide.

30.  Glume awns split into 3–9 divisions; lemma awns about 0.2 mm wide at the base; rachis internodes 3–5 mm long................................................................................. 20. E. multisetus

30.  Glume awns entire or split into 2–3 divisions; lemma awns about 0.4 mm wide at the base; rachis internodes 3–10(15) mm long.......................................................................... 21. E. elymoides

29.  Rachises not disarticulating at maturity; glumes 0–43 mm long including the awns, entire, straight or outcurving from well above the base; lowest floret in each spikelet functional; blades 2–25 mm wide.

31.  Glume bodies with 0–1(2) veins, linear or tapering from the base, 0.1–0.6 mm wide, 0–24 mm long including the awns, often differing in length by more than 5 mm, persistent after the florets disarticulate; rachis internodes 0.1–0.3(0.4) mm thick at the thinnest sections, often with longitudinal green bands along the sides.

32.  Spikelets widely divergent to patent at maturity; lemma awns usually straight, rarely slightly curving; glumes vestigial or 1–3 mm long, occasionally some unequal glumes up to 10(20) mm long and 0.1–0.2 mm wide but with no distinct vein; spikes more or less erect........ 19. E. hystrix

32.  Spikelets usually appressed, never widely divergent; lemma awns straight or curving; glumes sometimes vestigial, usually 1–24 mm long, 0.1–0.6 mm wide, often with 1(2) distinct veins; spikes erect, nodding, or pendent.

33.  Glumes 12–30 mm long including the awns, subequal; lemma awns straight to moderately curving; spikes erect to slightly nodding.

34.  Spikelets (6)9–15(22) mm long excluding the awns, each with 2–5 florets; lemma awns moderately outcurving at maturity; glumes (0.2)0.3–0.5(0.7)mm wide....... 9. E. interruptus (in part)

34.  Spikelets 18–40 mm long (excluding the awns), each with 3–8 florets; lemma awns straight to slightly curving at maturity; glumes 0.1–0.3(0.6) mm wide.

35.  Anthers 2.5–4 mm long; lemmas scabrous-hispid to thinly strigose, at least distally; spikes 4–12 cm long; internodes 3–6 mm long, without green lateral bands, with hispid dorsal angles................................................. 14.E. pringlei

35.  Anthers 4.5–6 mm long; lemmas smooth, glabrous; spikes 9–20 cm long; internodes (5)7–15(22) mm long, with green lateral bands, glabrous except for the ciliolate margins....................................................................... 15. E. texensis

33.  Glumes 0–15(30) mm long including the awns, usually differing in length by at least 4 mm, 1 or both shorter than 12 mm, sometimes both essentially absent; lemma awns outcurving at maturity; spikes more or less nodding.

36.  Rachis internodes 4–6(9) mm long; lemmas hirsute to strigose, at least near the margins, awns 20–35 mm long; sheaths glabrous; plants not glaucous or moderately glaucous................................................................................. 18. E. diversiglumis

36.  Rachis internodes (4)6–13(18) mm long; lemmas glabrous or pubescent, awns (8)10–30(35) mm long; sheaths glabrous or villous; plants usually glaucous, sometimes strongly so.

37.  Lemmas usually glabrous, veins occasionally hispidulous near the apices, awns (8)10–20(25) mm long; spikelets with (3)4–5 florets; rachis internodes (4)6–10(12) mm long, without green lateral bands, glabrous; adaxial surfaces of the blades usually villous; plants strongly glaucous.................................... 16. E. svensonii

37.  Lemmas usually hairy, awns (10)20–30(35) mm long; spikelets with 3(5) florets; rachis internodes (5)7–13(18) mm long, with green lateral bands and hispid dorsal angles; adaxial surfaces of the blades glabrous or short-pilose; plants somewhat glaucous.................................................................................. 17. E. churchii

31.  Glume bodies with 2–5(8) veins, widening or parallel-sided above the base, (0.2)0.3–2.3 mm wide, 4–43 mm long including the awns, equal or subequal, persistent or disarticulating; rachis internodes 0.1–0.8 mm thick at the thinnest sections, usually lacking green lateral bands.

37.  Glume bases flat and veined or, if subterete to terete, indurate and without veins for less than 1 mm; glume bodies shorter than or subequal to the lowest lemmas; lemma awns usually flexuous to curving, sometimes straight; rachis internodes (2)3–14 mm long.

38.  Glumes with flat bases and hyaline or scarious margins, usually awned, awns 1–10 mm long, sometimes unawned; spikelets (1)2(3) per node, appressed to divergent, sometimes purplish; cauline nodes mostly exposed.

39.  Anthers 0.9–1.7 mm long; glumes 3–8 mm long; lowest lemmas 3–6 mm longer than the glumes, densely scabridulous to scabrous, awns usually outcurving; spikelets with (3)4–5(7) florets; spikes 2–5 cm wide, nodding to pendent; cauline nodes glabrous. 13. E. sibiricus (in part)

39.  Anthers 1.5–4.5 mm long; glumes (4.5)6–14(19) mm long; lowest lemmas from shorter than to 2.5 mm longer than the glumes, smooth, sometimes hairy, awns straight, flexuous, or outcurving; spikelets with 2–4(7) florets; spikes (0.2)0.5–2.5 cm wide, erect, nodding, or pendent; cauline nodes occasionally with short hairs.

40.  Glume bodies (6)9–14(19) mm long; lemmas 8–16 mm long, awns usually straight to flexuous; auricles usually present, to 2.5 mm long.... 10. E. glaucus (in part)

40.  Glume bodies (4.5)6–10(11) mm long; lemmas 5–14 mm long, awns flexuous to moderately outcurving; auricles often absent, or to 1.5 mm long.

41.  Lemmas with hairs, the marginal hairs markedly longer than those elsewhere; paleas acute; spikes nodding to pendent; rachis internodes 3–12 mm long; leaves usually deep green; plants native to the Pacific coastal mountains.......................................................................... 11. E. hirsutus

41.  Lemmas smooth, scabrous, or hispid, the marginal hairs, if present, not markedly longer than those elsewhere; paleas obtuse or truncate; spikes erect to slightly nodding; rachis internodes 3–6 mm long; leaves usually pale green, sometimes glaucous; plants introduced...................... 12. E. dahuricus

38.  Glumes with more or less terete bases, without hyaline or scarious margins, always awned, awns (5)8–25(27) mm long or the glume bodies indistinguishable from the awns; spikelets (1)2–3(5) per node, spreading, not or rarely purplish; cauline nodes usually concealed by the sheaths.

42.  Spikes erect to slightly nodding, internodes (5)8–14 mm long; glumes 0.2–0.5(0.7) mm wide; lemmas 7–10 mm long, usually smooth or scabrous, occasionally hirtellous, especially near the margins, awns 15–22 mm long, straight to moderately outcurving; blades 3–9 mm wide; culms (40)60–100(120) cm tall, nodes usually exposed........................................................................... 9. E. interruptus (in part)

42.  Spikes usually nodding to pendent, sometimes erect, internodes (2)3–8(12) mm long; glume bodies (0.2)0.4–1.6 mm wide; lemmas 8–15 mm long, glabrous or uniformly hairy, awns (10)15–40(50) mm long, moderately to strongly outcurving; blades 3–24 mm wide; culms (40)60–180(220) cm tall, nodes usually concealed by the leaf sheaths.

43.  Rachis internodes (2)3–5(7) mm long; spikelets 2(3) at most nodes, occasionally 1 or up to 5 at some nodes; paleas acute; blades (3)4–15(20) mm wide, usually firm and somewhat involute, dull green, drying grayish..................... 7. E. canadensis

43.  Rachis internodes 5–12 mm long; spikelets 2 per node; paleas narrowly truncate; blades (8)10–20(24) mm wide, flat, lax, dark green..................... 8. E. wiegandii

37.  Glumes bases more or less terete, indurate, and without veins for 0.5–4 mm; glume bodies exceeding the adjacent lemmas by 1–5 mm or indistinguishable from the glume awns; lemma awns usually straight, occasionally contorted on the lower spikelets; rachis internodes (1.5)2–5(8) mm long.

44.  Glumes persistent, glume bodies (0.2)0.3–0.8(1) mm wide, with 2–4 veins, the basal 0.5–2 mm straight or slightly curving; lemmas with hairs or scabrous; spikelets with 1–3(4) florets; spikes nodding, exserted from sheath.

45.  Adaxial surfaces of the blades densely villous with fine whitish hairs, rarely just pilose on the veins, dark glossy green; spikes 4–12 cm long; internodes (1.5)2–3(4) mm long; spikelets with 1–2(3) florets; lemmas usually villous, sometimes glabrous, sometimes scabrous, 5.5–9 mm long, 0.5–1.5 mm longer than the paleas; anthesis usually in early June to early July...................................................................... 5. E. villosus

45.  Adaxial surfaces of the blades glabrous or scabrous, dull green; spikes 7–25 cm long; internodes 3–5(8) mm long; spikelets with 2–3(4) florets; lemmas hispidulous or scabrous, 7–14 mm long, 1–5 mm longer than the paleas; anthesis usually in late June to late July....................................................................................... 6. E. riparius

44.  Glumes disarticulating, glume bodies (0.5)0.7–2.3 mm wide, with (2)3–5(8) veins, the basal 1–4 mm clearly bowed out; lemmas often glabrous, sometimes scabrous; spikelets with 2–5(6) florets; spikes erect, exserted or sheathed.

46.  Spikes (0.5)0.7–2.2(2.5) cm wide including the awns, exserted or sheathed; glume awns 0–10(15) mm long; spikelets appressed to slightly spreading; blades usually glabrous or scabridulous.

47.  Lemma awns 5–15(20) mm long at midspike; blades of all leaves usually spreading or lax and flat, those of the lower leaves not markedly larger or more persistent than those of the upper leaves; anthesis in mid-June to mid-August, usually 1–2 weeks earlier than sympatric E. curvatus.................. 3. E. virginicus

47.  Lemma awns 0.5–3(4) mm long at midspike; upper blades usually ascending and somewhat involute, blades of the lower leaves relatively short, narrow, and senescing earlier than those of the upper leaves; anthesis usually in late June to early August, 1–2 weeks later than sympatric E. virginicus............ 4. E. curvatus

46.  Spikes (1.7)2.2–4.5(5.5) cm wide including the awns, exserted; glume awns (10)15–30 mm long; spikelets spreading; blades glabrous or villous 48

48.  Spikes with (6)9–16(20) nodes; internodes 4–7 mm long, about 0.3 mm thick at the thinnest portion; blades lax, dark glossy green under the glaucous bloom; auricles 2–3 mm long, often purplish black, at least in the central range of the species; anthesis usually in mid-May to mid-June E. macgregorii

48.  Spikes with (10)18–30(36) nodes; internodes 3–5 mm long, 0.3–0.8 mm thick at the thinnest portion; blades lax, or ascending and involute, usually dull green, with or without a glaucous bloom; auricles 0–2 mm long, usually purplish brown; anthesis usually in mid-June to late July E. glabriflorus

Elymus macgregorii R. Brooks & J.J.N. Campb.

Early Wildrye

Plants cespitose, not rhizomatous, usually glaucous. Culms 40–120 cm, erect or slightly decumbent; nodes 4–8, mostly exposed, glabrous. Leaves evenly distributed; sheaths usually glabrous, rarely villous; auricles 2–3 mm, usually purplish black when fresh, sometimes light brown; ligules shorter than 1 mm; blades 7–15 mm wide, lax, dark glossy green under the glaucous bloom, adaxial surfaces usually glabrous, occasionally villous. Spikes 4–12 cm long, (1.7)2.2–3(4)4 cm wide, erect, exserted, with (6)9–16(20) nodes and 2 spikelets at all or most nodes, sometimes with 3 at some nodes; internodes 4–7 mm long, about 0.3 mm thick and 2-angled at the thinnest sections, usually glabrous or scabridulous beneath the spikelets. Spikelets 10–15 mm, strongly divergent, glaucous, maturing to pale yellowish brown, with (2)3–4 florets, lowest florets functional; disarticulation below the glumes and each floret, the lowest floret often falling with the glumes. Glumes subequal, entire, the basal 1–3 mm terete or subterete, indurate, without evident venation, moderately bowed out, glume bodies 8–16 mm long, 1–1.8 mm wide, linear-lanceolate, widening or parallel-sided above the base, (2)4–5(8)-veined, usually glabrous, occasionally hirsute, sometimes scabrous, margins firm, awns (10)15–20(25) mm, straight except the awns of yhe lowest spikelets occasionally contorted; lemmas 6–12 mm, usually glabrous, sometimes scabrous, occasionally villous, awns (15)20–30 mm, straight; paleas 6–10 mm, apices obtuse; anthers 2–4 mm. Anthesis usually mid-May to mid-June. 2n = 28.

Elymus macgregorii grows in moist, deep, alluvial or residual, calcareous or other base-rich soils in woods and thickets, mostly east of the 100th Meridian in the contiguous United States . It used to be confused with Elymus glabriflorus  or E. virginicus , but it reaches anthesis about a month earlier than sympatric populations of these species. In most of its range, E. macgregorii has purplish black auricles; light brown auricles may be locally abundant, particularly in populations at the limits of its range.

Elymus macregorii hybridizes with several species, but especially E. virginicus and E. hystrix  (Campbell 2000). Western plants often have smaller, more condensed spikes, suggesting a transition to E. virginicus var. jejunus , but often with distinctly villous leaves. Transitions to E. virginicus var. jejunus can also be recognized to the north, where the dates of anthesis are delayed, but even in Maine, E. macgregorii reaches anthesis about 10 days earlier than E. virginicus (Campbell and Haines 2002). Plants with villous lemmas grow at scattered locations; they have not been reported in distinct habitats, nor in large enough populations to warrant taxonomic recognition.

2. Elymus glabriflorus (Vasey ex L.H. Dewey) Scribn. & C.R. Ball

Southeastern Wildrye

Plants cespitose, not rhizomatous, often glaucous. Culms 60–140 cm, erect; nodes 6–9, mostly concealed, glabrous. Leaves evenly distributed; sheaths glabrous or pubescent, often reddish brown; auricles absent or to 2 mm, usually purplish brown; ligules shorter than 1 mm; blades 7–15 mm wide, lax or somewhat involute and ascending, usually dull green, sometimes with a glaucous bloom, adaxial surfaces glabrous or densely short-villous. Spikes 6–20 cm long, (2)2.5–4(5.5) cm wide, erect, exserted, with (10)18–30(36) nodes, usually with 2(3) spikelets per node, occasionally with up to 5 at some nodes; internodes 3–5 mm long, 0.3–0.8 mm thick and usually 4-angled at the thinnest sections, glabrous or pubescent beneath the spikelets. Spikelets 10–20 mm, strongly divergent, often reddish brown at maturity, with (2)3–5(6) florets, lowest florets functional; disarticulation below the glumes and each floret, or the lowest floret often falling with the glumes. Glumes equal or subequal, entire, the basal 1–3 mm terete, indurate, moderately bowed out, without evident venation, glume bodies 7–18 mm long, (0.7)0.9–1.7 mm wide, linear-lanceolate, widening above the base, (3)4–5(7)-veined, smooth or scabrous, sometimes hirsute, margins firm, awns (10)15–25(30) mm, straight except the awns of the lowest spikelets frequently contorted; lemmas 6–13 mm, smooth, scabrous, or hirsute, awns (15)25–35(40) mm, straight except the awns of the lowest spikelets occasionally contorted; paleas 6–12 mm, obtuse; anthers 2–4 mm. Anthesis usually mid-June to late July. 2n = 28.

Elymus glabriflorus grows on moist, damp, or dry soil in open woods, thickets, and tall grasslands, sometimes spreading into old fields and roadsides. It is found in most of the southeastern United States , extending north to Iowa, Illinois, Indiana, West Virginia, and along the Atlantic coast to Maine; it is rare north of Maryland. Anthesis is usually 2–4 weeks later than in E. virginicus  and other sympatric taxa, even in Texas, where it occurs up to a month earlier than the dates given (Davies 1980).

Elymus glabriflorus varies greatly in its pubescence, but without clear taxonomic relevance. Plants that combine pubescent spikelets and, usually, pubescent leaves with somewhat shorter spikes (6–12 cm versus 9–20 cm) and lemmas (6–10 mm versus 7–13 mm) are typical on relatively dry, infertile soils, especially in hilly interior regions, and are less frequent on the southeastern coastal plain. They have been named E. glabriflorus var. australis (Scribn. & C.R. Ball) J.J.N. Campb.  In contrast, glabrous to scabrous plants that are often more robust usually grow on relatively moist or damp soils of bottomlands and upland depressions.

Elymus glabriflorus is most closely related to E. macgregorii  and E. virginicus, forming occasional hybrids with both (Campbell 2000). It is sometimes confused with E. villosus , from which it differs in having erect spikes, and glumes that are bowed out and disarticulate at maturity. It has also been confused with E. canadensis , especially E. canadensis var. robustus , which may be derived from introgressants between the two species (Davies 1980). Hybrids with E. hystrix  are also known, with apparent introgression at some range margins, but artificial crosses with other species failed in several cases (Church 1967a, 1967b).

3. Elymus virginicus L.

Virginia Wildrye , Ιlyme de Virginie

Plants cespitose, not rhizomatous, sometimes glaucous, especially in the spikes. Culms 30–130 cm, erect to slightly decumbent; nodes 4–9, concealed or exposed, usually glabrous, rarely pubescent. Leaves evenly distributed; sheaths usually glabrous, rarely hirsute, occasionally reddish or purplish; auricles absent or to 1.8 mm, pale brown; ligules shorter than 1 mm; blades 2–14(18) mm wide, usually spreading or lax, sometimes becoming involute, basal blades similar to the upper blades, adaxial surfaces usually smooth , sometimes scabridulous, usually glabrous, occasionally pubescent. Spikes (3)4–16(22) cm long, 1–2.2(2.5) cm wide, erect, the bases often sheathed, with 2 spikelets per node, rarely with 3 at some nodes; internodes 3–5 mm long, 0.25–0.5 thick at the thinnest sections, smooth and glabrous, or scabrous, or with hairs beneath the spikelets. Spikelets 10–15 mm, appressed to slightly divergent, with (2)3–4(6) florets, lowest florets functional; disarticulation below the glumes and each floret, or the lowest floret often falling with the glumes. Glumes subequal or equal, the basal 1–4 mm terete, indurate, without evident venation, bowed out, yellowish, glume bodies 7–15 mm long, (0.5)0.7–2.3 mm wide, linear-lanceolate, widening above the base, 3–5(8)-veined, usually smooth or scabridulous, margins firm, awns 3–10(15) mm, straight; lemmas 6–10 mm, scabridulous, glabrous or villous-hirsute, awns (5)8–20(25) mm, straight; paleas 5–9 mm, obtuse; anthers 2–3.5(4) mm. Anthesis usually mid-June to late July (mid-August). 2n = 28.

Elymus virginicus is widespread in temperate North America, growing as far west as British Columbia and Arizona. It is infrequent to rare in the Rocky Mountains, western Great Plains, and southeastern coastal plain. It is a complex species, divided here into four intergrading varieties.

1.  Spikelets hispidulous to villous-hirsute, usually glaucous; anthesis usually in early July to mid-August           var. intermedius

1.  Spikelets usually glabrous or scabrous, glaucous or not; anthesis usually in mid-June to late July.

2.  Spikes partly sheathed; glumes 1–2.3 mm wide, strongly indurate and bowed out in the basal 2–4 mm; plants not glaucous, becoming yellowish brown or occasionally somewhat purplish at maturity     var. virginicus

2.  Spikes exserted; glumes (0.5)0.7–1.5(1.8) mm wide, moderately indurate and bowed out in the basal 1–2 mm; plants usually glaucous, becoming yellowish or reddish brown at maturity.

3.  Culms usually 70–100 cm long, with 6–8 nodes; blades 3–15 mm wide, flat; spikes 4–20 cm long, not strongly glaucous; glumes indurate only in the basal 1 mm.. var. jejunusvar. jejunus

3.  Culms usually 30–80 cm long, with 4–6 nodes; blades 2–9 mm wide, often becoming involute; spikes 3.5–11 cm long, often strongly glaucous; glumes usually indurate in the basal 1–2 mm  var. halophilusvar. halophilus

Elymus virginicus var. halophilus (E.P. Bicknell) Wiegand

Plants glaucous, often strongly so, becoming reddish brown at maturity. Culms usually 30–80 cm; nodes usually 4–6, often exposed; ligules and auricles often pronounced. Blades 2–9 mm wide, often becoming involute and ascending, glabrous or slightly scabrous. Spikes 3.5–11 cm, exserted; spikelets usually glabrous to scabrous, strongly glaucous; glumes about 0.7–1.5 mm wide, usually somewhat indurate and bowed out in the basal 1–2 mm. Anthesis late June to late July.

Elymus virginicus var. halophilus grows in the moist to damp soil of dunes and brackish marsh edges along the northern Atlantic coast, from Nova Scotia to North Carolina. It could be considered a relatively small, disjunct form of the largely midwestern E. virginicus var. jejunus , but its glumes are more like those of var. virginicus . Transitions to E. glabriflorus  may be found in southern regions. Rare northern plants with hirsute spikelets (sometimes called E. virginicus forma lasiolepis Fernald ) differ from var. intermedius by their grayish green, involute blades.

Elymus virginicus var. intermedius (Vasey ex A. Gray) Bush

Plants often partly glaucous, becoming yellowish, reddish, or slightly purplish brown at maturity. Culms usually 60–120 cm; nodes usually 4–8, concealed or exposed; auricles and ligules usually poorly developed. Blades 4–18 mm wide, lax or involute, glabrous, scabridulous, or occasionally pubescent. Spikes 6–22 cm long, sheathed or exserted; spikelets hispidulous to villous-hirsute, usually glaucous; glumes 0.8–1.2(2) mm wide, indurate and bowed out in the basal 2–4 mm. Anthesis early July to mid-August.

Elymus virginicus var. intermedius grows in moist, base-rich soil in open forests and thickets, especially on rocky, gravelly, or sandy banks of larger streams. It occurs from the central and southern Great Plains, through the central Mississippi and Ohio valleys, to the northeastern United States and adjacent Canada , but is rare to absent south of Oklahoma to Tennessee and to Maryland.

Elymus virginicus var. jejunus (Ramaley) Bush

Plants usually glaucous, but not strongly so, becoming yellowish or reddish brown at maturity. Culms (50)70–100(130) cm; nodes usually 6–8, often exposed; auricles and ligules often pronounced. Blades 3–15 mm wide, flat, usually scabridulous, rarely pubescent. Spikes 4–20 cm, exserted; spikelets usually glabrous to scabrous, sometimes glaucous; glumes (0.5)0.7–1.2(1.8) mm wide, indurate and bowed out only in the basal 1 mm. Anthesis mid-June to late July.

Elymus virginicus var. jejunus grows in moist to dry, sometimes alkaline or saline soil, in open, rocky, or alluvial woods, grasslands, glades, and disturbed places. It occupies the western range of the species, except for the Intermountain region. It is uncommon in the northeast, from Virginia to Newfoundland, and rare or absent in the southeast, beyond Texas and Indiana. It intergrades with var. virginicus  (with spikes up to 22 cm long in intermediate plants) in the Great Plains, and with E. glabriflorus  or E. macgregorii  in some southern or eastern regions. Spike exsertion, and thus the ease of distinction from var. virginicus, can be influenced by the environment (Brooks 1974). Some northern populations, from Alberta and North Dakota to Michigan and Quebec, especially on damper soils, have blades that are villous-hirsute and often darker green (e.g., Booher and Tryon 1948). Blades are often only 4–8 mm wide in the Great Plains, and some exceptionally small northern plants (E. virginicus var. micromeris Schmoll ) have blades (1)2–4(5.5) mm wide, spikes 3.2–7 cm long, glume awns 1–1.5 mm long, and lemma awns 3.5–13 mm long, suggesting a transition to E. curvatus  (see discussion under Elymus_curvatus).

Elymus virginicus L. var. virginicus

Plants not glaucous, usually becoming yellowish brown, occasionally somewhat purplish at maturity. Culms (30)40–90(130) cm; nodes usually 4–8, concealed or exposed; auricles and ligules sometimes pronounced. Blades 3–18 mm wide, lax or involute, usually scabridulous, rarely pubescent. Spikes 4–16(22) cm, partly sheathed; spikelets smooth or scabridulous, not glaucous; glumes 1–2(2.3) mm wide, indurate and bowed out in the basal 2–4 mm. Anthesis mid-June to late July.

Elymus virginicus var. virginicus grows in moist to damp or rather dry soil, mostly on bottomland or fertile uplands, in open woods, thickets, tall forbs, or weedy sites. It is widespread and abundant in the eastern range of the species, but also overlaps with var. jejunus  in the Great Plains, east to Texas and Manitoba. Its dimensions have much genetic and phenotypic variation (Brooks 1974). It occasionally hybridizes with sympatric Elymus species, including E. riparius , and even with Hordeum  (Bowden 1958; Church 1958; Pohl 1959; Nelson and Tyrl 1978). In its eastern range, most plants are distinctively short, reaching only 30–90 cm, with sheathed spikes 6–10 cm long. In more open or drier environments, especially in midwestern regions, plants are often more glaucous, robust, and exserted, grading into var. jejunus. Awn length increases towards the south, suggesting introgression with E. glabriflorus (Davies 1980). Pubescent blades are generally absent, but appear more frequently in Wisconsin and perhaps other northern areas.

4. Elymus curvatus Piper

Awnless Wildrye

Plants cespitose, not rhizomatous, often glaucous. Culms 60–110 cm, stiffly erect, or the base sometimes geniculate; nodes 6–9, concealed or exposed, glabrous. Leaves evenly distributed; sheaths glabrous, often reddish brown; auricles to 1 mm, sometimes absent; ligules shorter than 1 mm, ciliolate; blades 5–15 mm wide, the lower blades usually lax, shorter, narrower, and senescing earlier, the upper blades usually ascending and somewhat involute, adaxial surfaces smooth or scabridulous, occasionally scabrous. Spikes 9–15 cm long, (0.5)0.7–1.3 cm wide, erect, exserted or the bases slightly sheathed, with 2 spikelets per node; internodes 2.5–4.5 mm long, about 0.25–5 mm thick at the thinnest sections, smooth or scabrous beneath the spikelets. Spikelets 10–15 mm, appressed, often reddish brown at maturity, with (2)3–4(5) florets, lowest florets functional; disarticulation below the glumes and beneath the florets, or the lowest floret falling with the glumes. Glumes equal or subequal, the basal 2–3 mm terete, indurate, strongly bowed out, without evident venation, glume bodies 7–15 mm long, 1.2–2.1 mm wide, linear-lanceolate, widening, 3–5-veined, usually glabrous or scabrous, occasionally hispidulous, rarely hirsute on the veins, margins firm, awns 0–3(5) mm; lemmas 6–10 mm, glabrous or scabrous, rarely hirsute, awns (0.5)1–3(4) mm, rarely 5–10 mm on the lemmas of the distal spikelets, straight; paleas 6–10 mm, obtuse, often emarginate; anthers 1.5–3 mm. Anthesis late June to mid August. 2n = 28, 42.

Elymus curvatus grows in moist or damp soils of open forests, thickets, grasslands, ditches, and disturbed ground, especially on bottomland. It is widespread from British Columbia and Washington, through the Intermountain region and northern Rockies, to the northern Great Plains. It is infrequent or rare in the midwest, the Great Lakes region, and the northeast, and is virtually unknown in the southeast. It is similar to Elymus virginicus , and has sometimes been included in that species as E. virginicus var. submuticus Hook. , but it is more distinct than the varieties of E. virginicus treated above. Although E. virginicus and E. curvatus overlap greatly in range, E. curvatus usually has a distinct growth form, and its anthesis is 1–2 weeks later (Brooks 1974). Its spikes range from being completely exserted, especially west of the Great Plains, to largely sheathed, especially east of the Mississippi River and in more stressed environments. This geographic trend parallels that within E. virginicus, but sheathed plants of E. curvatus can usually be distinguished by their short awns. Clear transitions to E. virginicus, usually var. jejunus , are rare, but, especially from Missouri to Wisconsin, there are occasional plants with 5–10 mm awns on a few lemmas, especially at the spike tips. Rarely, plants from Missouri and Iowa to Quebec have hispid to hirsute spikelets, suggesting introgression with E. virginicus var. intermedius . There are few records of apparent hybrids with other species.

5. Elymus villosus Muhl.

Downy Wildrye

Plants cespitose, not rhizomatous, often persistently deep green. Culms 40–130 cm, erect; nodes 4–8, concealed or exposed, glabrous. Leaves evenly distributed; sheaths villous-hirsute, pilose, or occasionally glabrate, occasionally reddish brown; auricles 1–3 mm, brownish; ligules less than 1 mm, entire or erose; blades 4–12 mm wide, lax, dark glossy green, adaxial surfaces densely velutinous-villous with fine whitish hairs, or rarely pilose only on the veins. Spikes 4–12 cm long, 1.5–3.5 cm wide, slightly or strongly nodding, exserted, with 2 spikelets per node, or rarely with 1 or 3 at a few nodes; internodes (1.5)2–3(4) mm long, 0.15–0.25 mm thick at the thinnest sections, usually hairy below the spikelets, rarely glabrous. Spikelets 7–12 mm, moderately divergent, with 1–2(3) florets, lowest florets functional; disarticulation above the glumes and beneath each floret. Glumes equal, 12–25 mm including the often undifferentiated awns, the basal 0.5–2 mm terete, slightly indurate, straight or nearly so, without evident venation, glume bodies 7–10 mm long, (0.2)0.3–0.8 mm wide, linear-setiform, widening or parallel-sided above the base, 2–3(4)-veined, usually hirsute to hispid, occasionally scabrous to scabridulous, margins firm, awns 5–15 mm, straight; lemmas 5.5–9 mm, usually villous with fine, whitish, spreading hairs, especially near the margins and apices, sometimes glabrous or with coarser hairs, sometimes scabrous, awns 9–33 mm, straight; paleas 5–7.5 mm, obtuse, occasionally emarginate; anthers (1.6)2–3(4) mm. Anthesis early June to early July. 2n = 28.

Elymus villosus grows in moist to moderately dry, often rocky soils in woods and thickets, especially in calcareous or other base-rich soils, but it is also frequent on drier, sandy soils or damper, alluvial soils in glaciated regions. It extends from the Great Plains east to southern Quebec, northern New York, and Vermont south to Texas, Georgia, and South Carolina. It is absent from the southern portion of the coastal plain.

Elymus villosus is relatively uniform and distinct, although it has sometimes been confused with hairy plants of E. canadensis  and E. glabriflorus . The hairs of E. villosus are fine, whitish, and consistently dense on the leaf blades, typically spreading in the spikelets; the hairs of the other species are typically stouter and more appressed in the spikelets. Plants called E. villosus var. arkansanas (Scribn. & C.R. Ball) J.J.N. Campb.  are scabrous to glabrous in the spikes, except for the ciliate rachis margins, and often more robust. These are scattered over much of the species’ range, except in the north (from Wisconsin to New England), and are locally more frequent than typical plants in the Ozark Mountains and other midwestern hills. Some other western plants (including those called E. striatus var. ballii Pammel ) have unusually large, almost erect spikes, suggesting introgression from E. virginicus . There are rare apparent hybrids with species in the E. virginicus group, but the only proven natural hybrid is with Hordeum jubatum  (see ΧElyhordeum ). Artificial crosses with several species failed to produce healthy F1 plants (Church 1958).

6. Elymus riparius Wiegand

Eastern Riverbank Wildrye , Ιlyme des Rivages

Plants cespitose, not rhizomatous, often somewhat glaucous. Culms 70–160 cm, erect, sometimes rooting at the lower nodes; nodes 5–10, mostly concealed, glabrous. Leaves evenly distributed; sheaths usually glabrous or scabridulous, often reddish brown; auricles absent or to 2 mm, brown; ligules shorter than 1 mm; blades (5)8–15(25) mm wide, flat, lax, dull green, drying to grayish, adaxial surfaces glabrous or scabrous. Spikes 7–25 cm long, 2–4 cm wide, nodding, exserted, usually with 2 spikelets per node, rarely with 3 at some nodes; internodes 3–5(8) mm long, 0.2–0.35 thick at the thinnest sections, usually glabrous below the spikelets. Spikelets 10–20 mm, strongly divergent, with 2–3(4) florets, lowest florets functional; disarticulation above the glumes and beneath each floret. Glumes equal or subequal, 14–30 mm including the sometimes undifferentiated awn, the basal 0.5–2 mm terete, indurate, straight or nearly so, veins not evident, glume bodies 9–17 mm long, (0.3)0.5–0.8(1) mm wide, linear-setiform, entire, widening or parallel-sided above the base, 2–3(4)-veined, usually hispidulous or scabrous, rarely glabrous, margins firm, awns (5)8–18 mm, straight; lemmas 7–14 mm, usually hispidulous, sometimes scabrous, awns 15–35 mm, usually straight, those of the basal spikelets occasionally contorted; paleas 6–9 mm, usually acute, sometimes obtuse to truncate, bidentate; anthers 2–2.7 mm. Anthesis late June to late July. 2n = 28.

Elymus riparius grows in moist, usually alluvial and often sandy soils in woods and thickets, usually along larger streams and occasionally along upland ditches. It is widespread in most of temperate east-central North America. It is rare in southern Ontario and Quebec, and the eastern Great Plains. It is virtually absent from the southeastern coastal plain.

Elymus riparius is relatively uniform and distinct. It is sometimes confused withE. canadensis , but that species has curving awns. It hybridizes occasionally with several other taxa, especially E. virginicus var. virginicus  and E. hystrix , but the hybrids produce only late, depauperate spikes or none at all (e.g., Church 1958).

7.Elymus canadensis L.

Great Plains Wildrye , Ιlyme du Canada

Plants loosely cespitose, rarely with rhizomes to 4 cm long and 1–2 mm thick, often glaucous. Culms (40)60–150(180) cm, erect or decumbent; nodes 4–10, mostly concealed by the leaf sheaths, glabrous. Leaves evenly distributed; sheaths smooth or scabridulous, glabrous or hirsute, often reddish brown; auricles 1.5–4 mm, brown or purplish black; ligules to 1(2) mm, truncate, ciliolate; blades (3)4–15(20) mm wide, usually firm, often ascending and somewhat involute, usually dull green, drying to grayish, adaxial surfaces usually smooth or scabridulous and glabrous, rarely sparsely hispid to villous. Spikes 6–30 cm long, 3–7 cm wide, usually nodding, sometimes pendent or almost erect, usually with 2(3) spikelets per node, occasionally to 5 at some nodes, rarely with 1 at some nodes but never throughout; internodes (2)3–5(7) mm long, or 5–10 mm long towards the base, 0.2–0.35 mm thick at the thinnest sections, glabrous or with a few hairs below the spikelets. Spikelets 12–20 mm excluding the awns, more or less divergent, with (2)3–5(7) florets, lowest florets functional; disarticulation usually above the glumes and beneath each floret, rarely also below the glumes. Glumes usually equal, occasionally subequal, 11–40 mm including the awns, the basal 0–1 mm subterete and slightly indurate, glume bodies 6–13 mm long, 0.5–1.6 mm wide, linear-lanceolate to subsetaceous, entire, widening or parallel-sided above the base, 3–5-veined, glabrous to scabrous-ciliate, rarely villous on the veins, margins firm, awns (5)10–25(27) mm, straight to outcurving; lemmas 8–15 mm, glabrous, scabrous, hispid, or uniformly villous with the hairs generally appressed, awns (10)15–40(50) mm, moderately to strongly outcurving, often contorted at the spike bases; paleas 7–13 mm, acute, usually bidentate; anthers 2–3.5 mm. Anthesis May to July. 2n = 28, rarely 42.

Elymus canadensis grows on dry to moist or damp, often sandy or gravelly soil on prairies, dunes, stream banks, ditches, roadsides, and disturbed ground, or, especially to the south, in thickets and open woods near streams. It is widespread in most of temperate North America, extending from the southwestern Northwest Territories to Coahuila, Mexico , being especially common in the Great Plains. Reports from California and the southeastern states appear to be based on misidentifications. E. canadensis is considered a good forage species.

Elymus canadensis is sometimes confused with E. riparius , from which it differs in having curved rather than straight awns; and with E. wiegandii , from which it differs in its less robust habit and narrower leaves. It can hybridize with Elymus glabriflorus , E. virginicus , E. hystrix  and allies, E. glaucus , E. trachycaulus , Pseudoroegneria spicata , and other species. Subsequent introgression may have contributed to much of the diversity within the genus (Pohl 1959; Brown and Pratt 1960; Nelson and Tyrl 1978; Davies 1980; Campbell 2002). The three varieties recognized here show clear differences in their typical expression and evidence some geographic separation, but they may prove to be artificial reference points within a more or less continuous variation (Sanders et al. 1979). Nevertheless, crossing barriers sometimes exist between the varieties, and even between some sympatric strains (Church 1954, 1958, 1967a).

1.  Lemmas usually villous or hispid; spikes nodding to almost pendent; internodes 4–7 mm long, often strongly glaucous             var. canadensis

1.  Lemmas usually smooth or scabridulous, occasionally hirsute; spikes usually nodding, occasionally almost erect; internodes 3–4 mm long, not strongly glaucous.

2.  Glumes not clearly indurate or bowed out at the base, awns 10–20 mm long; lemmas smooth or scabridulous, awns usually 20–30 mm long, moderately outcurving; spikes 6–20 cm long var. brachystachys

2.  Glumes often slightly indurate and bowed out at the base, awns 15–25 mm long; lemmas occasionally hirsute, awns 30–40 mm long, often strongly outcurving; spikes 15–25(30) cm long               var. robustus

Elymus canadensis var. brachystachys (Scribn. & C.R. Ball) Farw.

Spikes 6–20 cm, nodding, not strongly glaucous, often becoming yellowish or pale reddish brown, rarely with 3 spikelets per node; internodes mostly 3–4 mm. Glumes not clearly indurate or bowed out at the base, awns 10–20 mm; lemmas smooth or scabridulous, awns usually 20–30 mm, moderately outcurving.

Elymus canadensis var. brachystachys is widespread in the southern Great Plains from Nebraska to Texas, where anthesis is from March to early June. It also occurs sporadically as far north as southern Canada , from British Columbia to Quebec. Plants of this variety occasionally appear introgressed from E. virginicus , particularly E. virginicus var. jejunus , but not to the same extent as E. canadensis var. robustus .

Elymus canadensis L. var. canadensis

Spikes (6)10–25(30) cm, nodding to almost pendent, often strongly glaucous, often with 3 spikelets per node; internodes 4–7 mm. Glumes not clearly indurate or bowed out at the base, awns 10–25 mm; lemmas villous or hispid, awns 15–40 mm, moderately to strongly outcurving.

Elymus canadensis var. canadensis is widespread across the northern range of the species, where anthesis is from late June to August, but it is also frequent as far south as Arizona, New Mexico, and Oklahoma. Tentatively included here are E. canadensis var. glaucifolius (Muhl.) Torr. , which is strongly glaucous, with scabrous blades and hirsute or scabrous lemmas; plus E. canadensis var. villosus Bates , which has villous leaves and occurs rarely in the northern Great Plains.

Elymus canadensis var. robustus (Scribn. & J.G. Sm.) Mack. & Bush

Spikes 15–25(30) cm, moderately nodding, occasionally almost erect, not strongly glaucous, often becoming yellowish or pale reddish brown; internodes 3–4 mm. Glumes often slightly indurate and bowed out at the base, awns 15–25 mm; lemmas smooth to scabridulous, or occasionally hirsute, awns 30–40 mm, moderately or often strongly outcurving.

Elymus canadensis var. robustus occurs mostly in the east-central range of the species, from Illinois and Ohio to Oklahoma and Nebraska , locally becoming the most common variety. Anthesis can be earlier than in other sympatric E. canadensis varieties (Bush 1926). These rather heterogeneous plants tend to be large in most dimensions, and may have resulted from introgression with E. virginicus  or E. glabriflorus , with which they have often been confused (Davies 1980). F 1 hybrids of the other varieties with these species are similar to var. robustus , sometimes with erect spikes that are longer than those of either parent, but they are usually sterile. Spike pubescence may vary considerably, perhaps reflecting different hybrid origins.

8.Elymus wiegandii Fernald

Northern Riverbank Wildrye , Ιlyme de Wiegand

Plants cespitose, not rhizomatous, somewhat glaucous. Culms 100–180(220) cm, erect; nodes 9–16, mostly concealed by the leaf sheaths, glabrous. Leaves evenly distributed; sheaths usually glabrous, occasionally villous, often reddish brown; auricles 1–3 mm, brown; ligules to 1 mm; blades (8)10–20(24) mm wide, flat, lax, dark green, adaxial surfaces usually thinly pilose, with weak spreading hairs on the veins at least near the margins, sometimes villous or glabrous. Spikes 10–30 cm long, 3–5 cm wide, pendent, the bases often barely exserted, with 2 spikelets per node; internodes 5–8(12) mm long, 0.2–0.3 mm thick at the thinnest sections, usually pubescent beneath the spikelets. Spikelets 12–20 mm, divergent, with (3)4–6(7) florets, lowest florets functional; disarticulation above the glumes and beneath each floret. Glumes equal or subequal, 12–30 mm including the often undifferentiated awns, the basal 0.5–1 mm subterete and slightly indurate, glume bodies 7–12 mm long, (0.2)0.4–0.9(1.1) mm wide, linear-setiform, entire, widening or parallel-sided above the base, 1–3(5)-veined, glabrous, hispidulous or villous, especially near the margins, margins firm, awns (5)8–15(18) mm, straight or flexuous; lemmas 10–15 mm, usually uniformly appressed-villous, rarely scabrous-hirtellous or glabrous, awns 15–25(30) mm, moderately to strongly outcurving; paleas 9–14 mm, narrowly truncate, minutely bidentate; anthers 2–3.5 mm. Anthesis from mid-July to early August. 2n = 28.

Elymus wiegandii grows in moist or damp, rich, alluvial soil, especially on sandy river terraces and in woods and thickets, primarily from Saskatchewan through much of the Great Lakes region to Nova Scotia and Connecticut . It has abnormal neocentric chromosomes with meiotic irregularities that appear to limit the fertility of its hybrids, and even some crosses within the species (Vilkomerson 1950), and may be derived from hybrids between E. canadensis  and perhaps E. riparius . The latter species is similar to E. wiegandii and overlaps it in range and habitat within the Great Lakes region, where there are a few plants that appear to be hybrids between the two. Plants with scabrous-hirtellous or glabrous lemmas (E. wiegandii forma calvescens Fernald ) are known from Maine and New Hampshire.

Elymus wiegandii is often confused with sympatric E. canadensis and E. diversiglumis , but it has a distinctive robust, broad-leaved habit. It is intermediate between the two in spike density and glume development. Occasional plants with glabrous leaves and less pendent spikes suggest introgression from E. canadensis, but artificial crosses produced no fertile F1 plants (Church 1958).

9. Elymus interruptus Buckley

Southwestern Wildrye

Plants cespitose, not rhizomatous, usually glaucous. Culms usually (40)60–100(120) cm, erect or the bases somewhat decumbent; nodes 4–8, usually exposed, glabrous. Leaves evenly distributed; sheaths usually glabrous, occasionally hirsute; auricles 0–2 mm, pale or reddish brown; ligules to 1 mm; blades 3–9 mm wide, lax, pale green, adaxial surfaces densely short-pilose, hispidulous, or scabridulous, especially on the veins. Spikes 5–20 cm long, 2–5 cm wide, erect to slightly nodding, with 2 spikelets per node; internodes (5)8–14 mm long, 0.2–0.3 mm thick at the thinnest sections, without pronounced dorsal angles, often with green lateral bands, glabrous beneath the spikelets. Spikelets (6)9–15(22) mm, somewhat to strongly divergent, with 2–5 florets, lowest florets functional; disarticulation above the glumes and beneath each floret. Glumes subequal, 15–30 mm including the weakly differentiated awns, the basal 0–1 mm subterete and indurate, glume bodies, when distinguishable, about 6–10 mm long, (0.2)0.3–0.5(0.7) mm wide, linear-setiform to setaceous, entire, widening or parallel-sided above the base, 1–3-veined, glabrous or scabridulous, margins firm, awns straight or flexuous; lemmas 7–10 mm, smooth or scabridulous, occasionally hirtellous especially near the margins, awns 15–22 mm, straight to moderately outcurving; paleas 6–9 mm, obtuse or narrowly truncate, sometimes emarginate; anthers 2–4.5 mm. Anthesis May to July. 2n = 28.

Elymus interruptus grows in dry to moist, rocky soil, often in canyons, open woods, and thickets, in Arizona, New Mexico, western Texas, and northern Mexico . Apparent intermediates between E. interruptus and E. canadensis  have been collected north of the documented range of typical E. interruptus in Arizona, New Mexico, and Iowa. Plants in the Ozark and Ouachita mountains, especially in Arkansas, that were previously referred to E. interruptus are now included in E. churchii .

Elymus interruptus is a poorly understood southern species that, at one extreme, used to be included in Elymus canadensis  or, at the other extreme, used to include E. churchii, E. svensonii , and E. diversiglumis , three species that seem more closely allied to E. hystrix . Campbell (2002) suggested E. interruptus may have arisen from the introgression of E. hystrix or a related species into E. canadensis var. brachystachys . Artificial crosses between E. hystrix and E. canadensis were generally unsuccessful, but yielded some plants resembling E. interruptus (Church 1954). Elymus interruptus has been crossed with E. canadensis, E. hystrix, E. svensonii, E. virginicus , E. glabriflorus and E. diversiglumis; only the hybrids with  E. diversiglumis were completely sterile (Church 1954, 1967a; Brown and Pratt 1960).

10. Elymus glaucus Buckley

Common Western Wildrye , Blue Wildrye

Plants densely to loosely cespitose, sometimes weakly rhizomatous, often glaucous. Culms 30–210 cm, erect or slightly decumbent; nodes 4–7, mostly exposed, usually glabrous, sometimes puberulent. Leaves evenly distributed; sheaths scabrous or smooth, glabrous or, particularly those of the lower leaves, retrorsely puberulent to hirsute, often purplish; auricles usually present, to 2.5 mm, often purplish; ligules to 1 mm, truncate, erose-ciliolate or entire; blades 2–13(17) mm wide, usually lax, sometimes slightly involute, adaxial surfaces glabrous, scabrous, or strigose on the veins, sometimes pilose to villous. Spikes 5–21 cm long, (0.2)0.5–2 cm wide, erect to slightly nodding, rarely somewhat pendent, usually with 2 spikelets per node, sometimes with 1 at all or most nodes, rarely with 3 at some nodes; internodes 4–8(12) mm long, 0.15–0.5 mm thick at the thinnest sections, angles scabrous, glabrous below the spikelets. Spikelets 8–25 mm, sometimes purplish at higher latitudes and elevations, appressed to slightly divergent, with (1)2–4(6) florets, lowest florets functional; disarticulation above the glumes and beneath each floret. Glumes subequal, 3/4 as long as or equaling the adjacent lemmas, bases often overlapping, usually flat and thin with evident venation, glume bodies (6)9–14(19) mm long, 0.6–1.5(2) mm wide, linear-lanceolate, entire, widening above the base, (1)3–5(7)-veined, 2–3 veins extending to the apices, glabrous, veins smooth or evenly scabrous, margins 0.1–0.2 mm wide, whitish hyaline, tapering towards the apices, unawned or awned, awns to 5(9) mm, straight; lemmas (8)9–14(16) mm, glabrous, scabrous, or short-hirsute, awns (0)1–30(35) mm, usually straight to flexuous, sometimes slightly curving; paleas 7–13 mm, keels straight or slightly concave, usually scabrous to ciliate, apices often bidentate; anthers 1.5–3.5 mm. Anthesis from May to July. 2n = 28.

Elymus glaucus grows in moist to dry soil in meadows, thickets, and open woods. It is widespread in western North America, from Alaska to Saskatchewan, and south to Baja California and New Mexico. It is also sporadic, sometimes appearing transitional to E. trachycaulus , from the northern Great Plains to southern Ontario and New York and, as a disjunct, on rocky sites in the Ozark and Ouachita mountains.

Populations can differ greatly in morphology, especially in rhizome development, leaf width, pubescence, and the prevalence of solitary spikelets; their crossing relationships are partly correlated with such variation (Snyder 1950, 1951; Stebbins 1957, Wilson et al. 2001). Rhizome development and the production of solitary spikelets may also be environmental responses. Rhizomatous plants are more common on unstable slopes or sandy soils. Plants with solitary spikelets are more common on poor soil or in shade. They are often confused, particularly in the herbarium, with E. stebbinsii  or E. trachycaulus . They differ from E. stebbinsii in their shorter anthers and awned glumes. Distinction from E. trachycaulus can be difficult with herbarium specimens, but is generally easy in the field, E. glaucus having more evenly leafy culms, laxer and wider blades, more tapered glumes that are almost always awned, and shorter anthers than the sympatric E. trachycaulus.

There are reports of natural hybrids with several other species of Elymus, including E. elymoides , E. multisetus  (see E. Χhansenii , p. ??), E. trachycaulus, and E. stebbinsii. These hybrids often appear at least partially fertile. Elymus glaucus can also form intergeneric hybrids with Leymus  and Hordeum  (see ΧElyleymus , p. ??, and ΧLeydeum , p. ??).

The following three subspecies appear to be morphologically, ecologically, and geographically distinct. Plants found at elevations of up to 2200 m along the Pacific coast, with hairy leaf blades and lemma awns usually less than 20 mm long, have been called subsp. jepsonii (Burtt Davy) Gould , but Wilson et al. (2001) demonstrated that such plants are neither genetically nor ecologically distinct from those with glabrous leaf blades; they are included here in subsp. glaucus .

1.  Lemma awns (0)1–5(7) mm long; glume awns 0–2 mm long... subsp. virescens

1.  Lemma awns (5)10–30(35) mm long; glume awns (0.5)1–9 mm long.

2.  Blades 4–17 mm wide, adaxial surfaces glabrous or strigose, occasionally pilose to hirsute with hairs of fairly uniform length; glume awns (0.5)1–5(9) mm long............ subsp. glaucus

2.  Blades 3–8 mm wide, densely short-pilose with scattered longer hairs; glume awns 3–8 mm long subsp. mackenzii

Elymus glaucus Buckley subsp. glaucus

Sheaths glabrous, scabrous or pubescent; blades usually 4–17 mm wide, adaxial surfaces glabrous or strigose, occasionally pilose to hirsute with hairs of fairly uniform length. Glume awns (0.5)1–5(9) mm; lemma awns (5)10–25(35) mm.

Elymus glaucus subsp. glaucus grows throughout the range of the species, from sea level to 2500 m. It is absent from the area where E. glaucus subsp. mackenzii  grows. It resembles E. hirsutus , differing in its erect spikes and in the pattern of its lemma pubescence. It also resembles the introduced E. dahuricus , from which it differs in its palea shape.

Elymus glaucus subsp. mackenzii (Bush) J.J.N. Campb.

Sheaths usually puberulent; blades 3–8 mm wide, densely short-pilose, with scattered longer hairs. Glume awns 3–8 mm; lemma awns 20–30 mm.

Elymus glaucus subsp. mackenzii grows on limestone clifftops, rocky ledges, and glades, in open woods and thickets. It is known only from Arkansas, Missouri, and Oklahoma, at scattered sites in the Ozark Mountains and at Rich Mountain in the Ouachita Mountains. This subspecies is remarkably disjunct, at least 500 miles from the nearest known E. glaucus to the west and north.

Elymus glaucus subsp. virescens (Piper) Gould

Sheaths glabrous or scabrous; blades 2–10 mm wide, smooth or scabridulous to pubescent. Glume awns 0–2 mm; lemma awns (0)1–5(7) mm.

Elymus glaucus subsp. virescens generally grows in relatively dry or rocky soils along cliffs, bluffs, slopes, shores, and river banks, and in coniferous forests, chaparral, and other woodlands along the coast from Alaska to central California, at elevations from sea level to 1200 m.

Elymus hirsutus J. Presl

Northwestern Wildrye

Plants cespitose, sometimes shortly rhizomatous. Culms 40–140 cm, usually somewhat decumbent; nodes 4–7, mostly exposed, usually glabrous, occasionally puberulent. Leaves evenly distributed; sheaths usually glabrous and smooth, occasionally scabridulous or retrorsely hairy, sometimes purplish; auricles to 1.5 mm, often absent; ligules to 1 mm; blades 4–12 mm wide, lax, usually deep green, adaxial surfaces usually pilose or villous, occasionally puberulent or scabridulous. Spikes 6–20 cm long, 0.5–2 cm wide, nodding to pendent, with 2 spikelets per node, rarely with 3 at some nodes; internodes 3–10(12) mm long, 0.2–0.7 mm thick at the thinnest sections, usually glabrous, sometimes sparsely hairy. Spikelets 12–20 mm, appressed to divergent, sometimes purplish at higher latitudes, with 2–4(7) florets, lowest florets functional; disarticulation above the glumes and beneath each floret. Glumes equal or subequal, the bases flat, occasionally indurate for 0.5 mm, veins usually evident, glume bodies (4.5)7–10(11) mm long, 0.7–1.5 mm wide, linear-lanceolate, entire, widening or parallel-sided above the base, 3–5-veined, usually scabridulous to scabrous, veins occasionally hirsute beyond midlength, margins hyaline or scarious, awns 1–10 mm, straight; lemmas 7–14 mm, smooth or scabridulous, lateral veins hairy, margins hairy beyond midlength, marginal hairs 0.5–1 mm, longer than those elsewhere, awns (2)8–30 mm, flexuous to moderately outcurving; paleas 6–13 mm, with hairs of varying lengths on the keels and apices, acute, bidentate; anthers 2–3.5 mm. Anthesis from May to July. 2n = 28.

Elymus hirsutus grows in moist to damp or dry soils in woods, thickets, and grasslands. Its range extends along the coastal mountains from the Aleutian Islands to northern Oregon, and inland to eastern British Columbia. Plants in the southern part of the range tend to have villous leaves and more erect spikes with shorter, straighter awns.

Elymus hirsutus is similar to E. glaucus , but its more pendent spikes, lemma pubescence pattern, and shorter glumes enable most specimens to be readily identified. Intermediates do exist; it is not known whether they reflect introgression or extremes of variation. It also forms occasional hybrids with Leymus mollis  and Hordeum brachyantherum .

12. Elymus dahuricus Turcz. ex Griseb.

Plants cespitose, not rhizomatous, often glaucous. Culms 30–130 cm, erect; nodes 4–7, mostly exposed, usually glabrous, occasionally short-hairy. Leaves evenly distributed; sheaths glabrous; auricles minute or absent; ligules 0.5–1 mm; blades 3–18 mm wide, lax, usually pale green, sometimes glaucous, adaxial surfaces usually smooth or scabrous on the veins, sometimes sparsely pilose. Spikes 7–23 cm long, 1–2.5 cm wide, usually slightly nodding, sometimes erect, usually with 2 spikelets per node, occasionally with 1 spikelet at some nodes; internodes 3–6 mm long, 0.2–0.8 mm thick at the thinnest sections, angles usually with scattered hairs. Spikelets 10–15 mm, appressed to divergent, often purplish, with (2)3–4(5) florets, lowest florets functional; disarticulation above the glumes, beneath each floret. Glumes equal, the bases flat, not indurate, veins evident, glume bodies 6–9 mm long, 1–1.5 mm wide, linear-lanceolate, entire, widening or parallel-sided above the base, (1)3–5(7)-veined, veins scabrous, margins hyaline or scarious, awns (0)1–5 mm, straight or outcurving; lemmas (5)7–11 mm, usually glabrous and smooth throughout, sometimes scabrous to hispid distally and on the margins, marginal hairs not markedly longer than those elsewhere, awns (3)6–17(20) mm, usually somewhat outcurving from near the base; paleas 7–11 mm, keels spinose-ciliate, apices obtuse or truncate; anthers 1.5–3.5 mm. Anthesis from May to July. 2n = 42.

Elymus dahuricus is widespread in temperate central and eastern Asia. Like E. tsukushiensis  (p. ???), it is a hexaploid with an StYH genome constitution. It has been introduced for reclamation in some parts of western North America. It is treated here because it is most likely to be confused with E. glaucus , from which it differs in its palea shape. Because its presence in the Flora region became known shortly before completion of this treatment, its distribution in the region is not known. Several varieties have been described in Asia; only Elymus dahuricus Turcz. ex Griseb. var. dahuricus  has been introduced to North America.

13.  Elymus sibiricus L.

Siberian Wildrye

Plants usually cespitose, sometimes weakly rhizomatous, usually glaucous, occasionally strongly so. Culms 40–150 cm, erect or slightly geniculate at the base; nodes 6–9, usually exposed, glabrous. Leaves evenly distributed; sheaths glabrous or hirsute, often purplish; auricles to 1 mm, often absent; ligules to 1 mm; blades (3)5–14(16) mm wide, lax, adaxial surfaces usually pilose to hirsute on the veins, sometimes scabrous or smooth. Spikes 7–30 cm long, 2–5 cm wide, flexuous, nodding to pendent, with (1)2(3–4) spikelets per node, solitary spikelets usually basal or distal, rarely occurring throughout; internodes 5–10 mm long, 0.2–0.7 mm thick at the thinnest sections, mostly glabrous, sometimes scabrous below the spikelets, angles ciliate. Spikelets 10–18 mm, appressed to divergent, usually becoming purplish, with (3)4–5(7) florets, lowest florets functional; disarticulation above the glumes, beneath each floret. Glumes equal or subequal, the bases flat, evidently veined, not indurate, glume bodies 3–8 mm long, 0.4–1(1.2) mm wide, linear-lanceolate to subsetaceous, entire, widening or parallel-sided above the base, 3(5)-veined, veins smooth or scabrous, margins hyaline or scarious, awns 1–6 mm, straight; lemmas 8–13 mm, densely scabridulous to scabrous, at least along the outer veins, awns 10–25 mm, usually somewhat outcurving from near the base; paleas 8–12 mm, keels spinose-ciliate, bidentate, apices acute, 0.15–0.3 mm wide between the veins; anthers 0.9–1.7 mm. Anthesis from June to July. 2n = 28.

Elymus sibiricus grows in dry to damp grasslands and thickets, on slopes, eroding river banks, mud flats, coastal benches, dunes, clearings, and other disturbed areas, in southern Alaska, the southern Yukon Territory, the southwestern MacKenzie District in the Northwest Territories, and central British Columbia. Porsild and Cody (1980) suggested that at least some of the populations are native to North America. In a more extensive analysis, Bennett (2006) concluded that all North American populations are the result of recent introductions. The species is widespread in cool temperate regions of central and eastern Asia. In China , it is considered an excellent forage grass, having a high protein content.

North American plants differ from Asian plants in several respects: they are up to 150 cm tall, versus 90 cm in Asia; their leaves are usually pubescent, rather than glabrous to scabrous; and their lemmas are scabridulous to scabrous, rather than glabrous to strigulose or pilose.

14.  Elymus pringlei Scribn. & Merr.

Mexican Wildrye

Plants cespitose, not rhizomatous, usually somewhat glaucous. Culms 50–110 cm, erect or somewhat geniculate at the base; nodes 6–9, mostly exposed, glabrous. Leaves evenly distributed; sheaths usually glabrous, occasionally pilose, hairs somewhat retrorse; auricles about 1 mm, pale or brownish; ligules about 1 mm, erose; blades 3–12 mm wide, lax, adaxial surfaces sparsely scabridulous, sometimes hispidulous to pilose on the veins, usually glaucous. Spikes 4–12 cm long, 2–3 cm wide, erect, the bases sometimes sheathed, with 2 spikelets per node; internodes 3–6 mm, about 0.2 mm thick at the thinnest sections, with 2 hispid dorsal angles, without green lateral bands. Spikelets 10–15 mm excluding the awns, 18–30 mm including the awns, appressed, with 3–5(6) florets, lowest florets functional; disarticulation above the glumes, beneath each floret. Glumes subequal, 12–22 mm long including the undifferentiated awns, 0.2–0.3(0.6) mm wide, setaceous, entire, 0–1(2)-veined, tapering from the base, glabrous, margins firm, awns more or less straight; lemmas 8–10 mm, usually scabrous-hispid or thinly strigose, at least distally, awns 8–22 mm, straight or flexuous; paleas 7–8 mm, obtuse, often emarginate; anthers 2.5–4 mm. Anthesis May to June. 2n = unknown.

Elymus pringlei grows on moist slopes and canyons, in pine and deciduous tree woods, at 1500–2250 m in the Sierra Madre Orientale of eastern Mexico . This poorly known species is similar to Elymus texensis  and E. interruptus . It is included here because it seems likely that it also grows in southern Texas, having been collected in Coahuila, Mexico , 54 miles from the border, near Big Bend National Park (Campbell 2002).

15.  Elymus texensis J.J.N. Campb.

Texas Wildrye

Plants cespitose, not rhizomatous, glaucous. Culms 70–110 cm, erect; nodes 4–6, mostly exposed, glabrous. Leaves evenly distributed; sheaths glabrous; auricles to about 2 mm, pale to purplish brown; ligules 1–2 mm, erose; blades 2–9 mm wide, lax or somewhat involute, adaxial surfaces thinly scabrous to hirsute or densely pilose. Spikes 9–20 cm long, 2–2.5 cm wide, erect to slightly nodding, with 2 spikelets per node; internodes (5)7–15(22) mm long, 0.1–0.3 mm thick at the thinnest sections, glabrous except for the ciliolate margins, with slight dorsal angles and green lateral bands along the concave sides. Spikelets 13–20 mm excluding the awns, 20–40 mm including the awns, appressed, with 4–6(8) florets, lowest florets functional; disarticulation above the glumes, beneath each floret. Glumes subequal, 14–24 mm long including the undifferentiated awns, 0.1–0.3 mm wide, setaceous, entire, 0–1-veined, tapering from the base, glabrous, margins firm, awns more or less straight; lemmas 8–12 mm, smooth, glabrous, awns 8–25 mm, straight, flexuous or slightly curving; paleas about 7–11 mm, obtuse or truncate; anthers 4.5–6 mm. Anthesis in May. 2n = unknown.

Elymus texensis is known only from calcareous bluffs and hills in juniper woods and grassy areas on the Edwards Plateau of southwest Texas. It is known from only three collections and needs further study (Campbell 2002). It is similar to the Mexican species, Elymus pringlei , but differs in its larger anthers, larger, less pubescent spikelets, and in its longer, glabrous rachis internodes with green lateral bands.

16.  Elymus svensonii G.L. Church

Svenson’s Wildrye

Plants cespitose, not rhizomatous, strongly glaucous. Culms 50–110 cm, erect; nodes 6–8, mostly exposed, often reddish brown, glabrous. Leaves evenly distributed; sheaths glabrous or villous, often somewhat purplish; auricles 1–2 mm, purplish or reddish brown; ligules to 1 mm, often reddish brown; blades 4–8(10) mm wide, lax, usually pale green, adaxial surfaces usually villous. Spikes 10–16 cm long, 3–5 cm wide, nodding, with 2 spikelets per node; internodes (4)6–10(12) mm long, about 0.2 mm thick at the thinnest sections, flexuous, glabrous, without green lateral bands. Spikelets 10–16 mm, usually appressed, with (3)4–5 florets, lowest florets functional; disarticulation above the glumes, beneath each floret. Glumes usually differing in length by more than 5 mm, sometimes vestigial to absent from the upper spikelets or throughout, (0)1–15(18) mm long including the undifferentiated awns, indurate at the base, 0.1–0.3 mm wide, setaceous to subulate, entire, 0–1-veined, tapering from the base, glabrous, margins firm, awns often curving outward; lemmas 8–10 mm, glabrous, veins occasionally hispidulous near the lemma apices, awns (8)10–20(25) mm, moderately to strongly outcurving at maturity; paleas 7–9 mm, obtuse or truncate, occasionally emarginate; anthers 3–5 mm. Anthesis from mid-June to early July. 2n = unknown.

Elymus svensonii grows in dry, rocky soils in open woods of the interior low plateaus, mostly along bluffs of the Kentucky River and its tributaries in the bluegrass region of Kentucky, and along bluffs of the Cumberland River and its Caney Fork in the central basin of Tennessee. Most sites are on Ordovician limestone, but its discovery by Natural Heritage programs in Kentucky along the Green River on Mississippian limestone, and in Tennessee along the Piney River on Silurian limestone, suggest that it may be more widespread. It has been a candidate for federal protection in the United States .

Elymus svensonii, like E. diversiglumis  and E. churchii , may be derived from hybrids between E. hystrix and E. canadensis (Church 1967a), even though E. canadensis currently has its eastern limit 50–100 miles west of most E. svensonii. Elymus svensonii hybridizes naturally with E. hystrix, E. virginicus and other species of Elymus. Plants with little glume development are frequent; they appear to be introgressed by E. hystrix. Artificial crosses with E. interruptus have been successful, but those with E. diversiglumis have not (Church 1967a). Elymus svensonii resembles E. churchii; it differs in having less open spikes, shorter awns, more florets per spikelet, and more pubescent, glaucous foliage.

17.  Elymus churchii J.J.N. Campb.

Church’s Wildrye

Plants cespitose, not rhizomatous, often somewhat glaucous. Culms 50–120 cm, erect; nodes 4–8, exposed or concealed, often reddish brown or blackish, glabrous. Leaves evenly distributed; sheaths usually glabrous, sometimes pubescent at the summit; auricles 1–2 mm, often reddish brown or blackish; ligules to 1 mm, often reddish brown; blades 3–11 mm wide, lax, adaxial surfaces glabrous or short-pilose. Spikes 10–18 cm long, 3–5 cm wide, slightly nodding, with 2 spikelets per node; internodes (5)7–13(18) mm long, about 0.2 mm thick at the thinnest sections, flexuous, with green lateral bands, glabrous except the dorsal angles hispid. Spikelets 10–15 mm, usually appressed, with 3(5) florets, lowest florets functional; disarticulation above the glumes, beneath each floret. Glumes often differing in length by more than 5 mm, sometimes vestigial to absent from the upper spikelets or throughout, 0–15(20) mm long including the undifferentiated awns, indurate at the base, 0.1–0.3 mm wide, setaceous to subulate, entire, 0–1-veined, glabrous, margins firm, awns often outcurving; lemmas 8–10 mm, usually hairy, occasionally glabrous, awns (10)20–30(35) mm, slightly to strongly outcurving at maturity; paleas 7–9 mm, obtuse to truncate, sometimes emarginate; anthers 2.5–3 mm, evident in June. 2n = unknown.

Elymus churchii grows in dry, rocky, often relatively base-rich soils, in open woods on ridges, and on bluffs and river banks. Its range includes the central Ouachita Mountains and the western Ozark Mountains in Arkansas, Oklahoma, and Missouri.

Elymus churchii used to be included in Elymus interruptus  (Steyermark 1963; Smith 1991). It is similar to the more eastern, disjunct Elymus svensonii , from which it differs in its more open spikes, longer awns, fewer florets per spikelet, and less pubescent, less glaucous foliage. Like E. svensonii, E. churchii may have originated from hybridization between E. canadensis  and E. hystrix ; occasional intermediates with both species exist (Campbell 2002).

18.  Elymus diversiglumis Scribn. & C.R. Ball

Unequal-Glumed Wildrye

Plants cespitose, not rhizomatous, sometimes moderately glaucous. Culms 70–160 cm, erect; nodes 4–9, mostly exposed, glabrous. Leaves evenly distributed; sheaths glabrous, often purplish; auricles 1–2 mm, purplish or brownish black; ligules usually 1–2 mm; blades 5–17 mm wide, lax, adaxial surfaces usually pilose, at least on the veins, occasionally scabrous. Spikes 8–28 cm long, 3–5 cm wide, nodding to pendent, with 2 spikelets per node, rarely with 1 or 3 at a few nodes; internodes 4–6(9) mm long, 0.2–0.3 mm thick at the thinnest sections, margins and summits often pubescent. Spikelets 10–16 mm, appressed, with 2–4(5) florets, lowest florets functional; disarticulation above the glumes, beneath each floret. Glumes usually differing in length by at least (3)4 mm, occasionally obsolete, (1)2–15(20) mm long including the undifferentiated awns, indurate at the base, (0.1)0.2–0.4(0.6) mm wide, setaceous, 0–1-veined, tapering from the base, scabrous or hispidulous at least towards the apices, margins firm, awns often outcurving; lemmas 7–12 mm, usually silvery-hirsute to sericeous, occasionally hirtellous or strigose, at least near the margins, backs sometimes scabrous, awns 18–35 mm, moderately to strongly outcurving at maturity; paleas 7–10 mm, obtuse, occasionally emarginate; anthers 2–4 mm. Anthesis from early June to late July. 2n = 28.

Elymus diversiglumis grows in moist to dry, often base-rich and alluvial soils, in open woods, woodland margins, and thickets in the northern Great Plains, from Saskatchewan and Manitoba to Wyoming, Wisconsin, and Iowa.

Elymus diversiglumis is a variable species that, like E. svensonii  and E. churchii , may have originated from hybrids between Elymus canadensis var. canadensis and E. hystrix , although part of its range extends further west than the current distribution of the latter species. Elymus diversiglumis usually reaches anthesis 2–4 weeks earlier than sympatric populations of E. canadensis . Church (1954, 1958, 1967a) found that most artificial canadensis–hystrix hybrids, as well as some plants of E. diversiglumis itself, are sterile. Those that were not sterile could occasionally form fertile backcrosses with E. canadensis and, to a lesser extent, with E. hystrix. Introgressant populations involving all three species are known. Artificial crosses with other species have not been successful.

19.  Elymus hystrix L.

Bottlebrush Grass , Glumeless Wildrye

Plants cespitose, not rhizomatous, occasionally glaucous, particularly the spikes. Culms 50–140 cm, usually erect, occasionally geniculate below; nodes 4–8, exposed or concealed, glabrous. Leaves evenly distributed; sheaths usually glabrous, occasionally pilose, often purplish; auricles usually present, 0.5–3 mm, brown to black; ligules 1–2(3) mm; blades 4–16 mm wide, lax, usually deep glossy green, adaxial surfaces pilose or scabridulous. Spikes 7–20 cm long, 4–7 cm wide, more or less erect, usually with 2 spikelets per node, rarely with 3 at some nodes; internodes (3)4–8(10) mm long, (0.1)0.2–0.3(0.4) mm thick at the thinnest sections, flexuous, usually glabrous, sometimes scabrous or hirsute, usually with green lateral bands. Spikelets 10–18 mm, strongly divergent to patent at maturity, with (1)2–4(6) florets, lowest florets functional; disarticulation above the glumes, beneath each floret. Glumes usually vestigial, sometimes 1–3 mm long, about 0.1 mm wide, subulate, entire, with no evident veins, occasionally to 10(20) mm long including the undifferentiated awns and differing in length by more than 5 mm, 0.1–0.2 mm wide, setaceous, tapering from the base, usually glabrous, occasionally appressed-puberulent to strigose, sometimes scabrous, usually straight, rarely somewhat curving, margins firm; lemmas 8–11 mm, usually glabrous, occasionally appressed-puberulent to strigose, especially near the margins and apices, awns (12)20–40(47) mm, usually straight, rarely somewhat curving; paleas 7–11 mm, obtuse or truncate, occasionally emarginate; anthers 2.5–5 mm. Anthesis mid-June to early July. 2n = 28.

Elymus hystrix grows in dry to moist soils in open woods and thickets, especially on base-rich slopes and small stream terraces. It grows throughout most of temperate eastern North America, extending west to Manitoba and Oklahoma, but is absent from the southern portion of the coastal plain.

Plants with pubescent lemmas have been recognized as Elymus hystrix var. bigelovianus (Fernald) Bowden . These occur infrequently north of a line from South Dakota through Kentucky to New Jersey, and are often mixed with the typical variety; pure populations are known in the northeastern United States. Plants with pubescent blades are also more prevalent to the north.

Elymus hystrix hybridizes with most eastern species of Elymus. Introgression may account for the considerable variation in glume development and spikelet appression among these species. Lack of glumes may be a recessive character, with even slight glume development indicating introgression (Church 1967b). Plants with relatively well-developed, subequal glumes are presumed to be of hybrid origin. Such plants include most material from the Carolina piedmont region, where E. glabriflorus  is the most likely source of introgression. The relatively frequent hybrids with E. virginicus are usually sterile, but Church (1967b) made crosses through three segregating generations. Within the ranges of Elymus diversiglumis , E. svensonii , and E. churchii , there appear to be frequent introgressants between these species and E. hystrix. Further east, especially in the Appalachian regions of North Carolina, Virginia, West Virginia, and Maryland (including the shale barrens and nearby), there are scattered plants of E. hystrix with curving awns and, in a few cases, appressed spikelets (Campbell 2002). Whether these represent occasional variation within the E. hystrix gene pool, or whether they are outlying remnants of introgression with E. canadensis  during a past eastward extension, is unknown.

20.  Elymus multisetus (J.G. Sm.) Burtt Davy

Big Squirreltail

Plants cespitose, not rhizomatous. Culms 15–65 cm, erect to ascending, usually puberulent; nodes 4–6, mostly concealed, glabrous. Leaves evenly distributed; sheaths glabrous or white-villous; auricles usually present, 0.5–1.5 mm; ligules to 1 mm, truncate, entire or lacerate; blades 1.5–4(5) mm wide, often ascending and involute, adaxial surfaces scabrous, pilose, or villous. Spikes 5–20 cm long, 5–15 cm wide, erect, sometimes partially enclosed at the base, with 2 spikelets per node, rarely with 3–4 at some nodes; internodes 3–5(8) mm long, 0.1–0.3 mm thick at the thinnest sections, glabrous beneath the spikelets. Spikelets 10–15 mm, divergent, with 2–4 florets, lowest florets sterile and glumelike in 1 or both spikelets at each node; disarticulation initially at the rachis nodes, subsequently beneath each floret. Glumes subequal, (10)30–100 mm including the awns, the bases indurate and glabrous, glume bodies about (2)5–10 mm long, 1–2 mm wide, setaceous, 2–3-veined, margins firm, awns (8)25–90 mm, each split into 3–9 unequal divisions, scabrous, flexuous to outcurving from near the glume bases at maturity; fertile lemmas 8–10 mm, smooth or scabrous near the apices, 2 lateral veins extending into bristles to 10 mm, awns (10)20–110 mm long, about 0.2 mm wide at the base, divergent to arcuate; paleas 7–9 mm, veins usually extending into about 1 mm bristles, apices acute to truncate; anthers 1–2 mm. Anthesis from late May to June. 2n = 28.

Elymus multisetus grows in dry, often rocky, open woods and thickets on slopes and plains, from central Washington and Idaho to southern California, Colorado, and northwestern Arizona, and from sea level to 2000 m. It has also been reported from Baja California, Mexico . It usually grows in less arid habitats than E. elymoides subsp. elymoides , but the two taxa are sometimes sympatric.

Wilson (1963) reported a wide belt of introgression between E. multisetus and E. elymoides subsp. elymoides from southeastern California to southern Nevada, but not in other areas where they are sympatric. There are also probable hybrids with Elymus glaucus  and Pseudoroegneria spicata .

21.  Elymus elymoides (Raf.) Swezey

Plants cespitose, often glaucous, not rhizomatous. Culms 8–65(77) cm, erect or geniculate to slightly decumbent, sometimes puberulent; nodes 4–6, mostly concealed, usually glabrous, sometimes pubescent. Leaves evenly distributed; sheaths glabrous, scabrous, puberulent, or densely white-villous; auricles usually present, to about 1 mm, often purplish; ligules shorter than 1 mm, truncate, entire or lacerate; blades (1)2–4(6) mm wide, spreading or ascending, often involute, sometimes folded, abaxial surfaces glabrous to puberulent, adaxial surfaces scabrous, puberulent, hirsute, or white-villous. Spikes 3–20 cm long, 5–15 cm wide, erect to subflexuous, with 2–3 spikelets per node, rarely with 1 at some nodes; internodes 3–10(15) mm long, 0.1–0.4 mm thick at the thinnest sections, usually glabrous, sometimes puberulent beneath the spikelets. Spikelets 10–20 mm, divergent, sometimes glaucous, at least 1 spikelet at a node with 2–4(5) florets, 1–4(5) florets fertile, sometimes all florets sterile in the lateral spikelets; disarticulation initially at the rachis nodes, subsequently beneath each floret. Glumes subequal, 20–135 mm including the often undifferentiated awns, the bases indurate and glabrous, glume bodies 5–10 mm long, 1–3 mm wide, linear to setaceous, 1–3-veined, margins firm, awns 15–125 mm, scabrous, sometimes split into 2–3 unequal divisions, flexuous to outcurving from near the base at maturity; fertile lemmas 6–12 mm, glabrous, scabrous, or appressed-pubescent, 2 lateral veins extending into bristles to 10 mm, awns 15–120 mm long, about 0.4 mm wide at the base, often reddish or purplish, scabrous, flexuous to curved near the base; paleas 6–11 mm, veins often extending into bristles to 2(5) mm, apices acute to truncate; anthers 0.9–2.2 mm. Anthesis from late May to July. 2n = 28.

Elymus elymoides grows in dry, often rocky, open woods, thickets, grasslands, and disturbed areas, from sagebrush deserts to alpine tundra. It is widespread in western North America, from British Columbia to northern Mexico and the western Great Plains, and introduced in western Missouri, Illinois, and Kentucky. It is often dominant in overgrazed pinyon-juniper woodlands. Although palatable early in the season, the disarticulating, long-awned spikes irritate grazing animals later in the year.

Elymus elymoides intergrades with E. multisetus  in parts of its southern range ( Wilson 1963). It is sometimes confused with E. scribneri , but differs in having more than one spikelet per node, narrower glumes, and less tardily disarticulating rachises. Hybrids with several other species in the Triticeae  are known; they can often be recognized by their tardily disarticulating rachises. Named interspecific hybrids (and the other parent) are E. Χsaundersii  (E. trachycaulus ), E. Χpinaloensis  (E. arizonicus ), and possibly E. Χhansenii  (E. elymoides or E. multisetus  Χ E. glaucus ). Hybrids with E. sierrae  have not been named; they are common where the two species are sympatric. They have broader glume bases, shorter glume awns, and longer anthers than E. elymoides.

1.  Rachis nodes with 3 spikelets, the central spikelet usually with 2 fertile florets, the florets of the lateral spikelets rudimentary to awnlike; lemma awns 15–30 mm long..... subsp. hordeoides

1.  Rachis nodes usually with 2 spikelets, each spikelet usually with (1)2–4(5) fertile florets; lemma awns 15–120 mm long.

2.  No spikelets appearing to have 3 glumes, the lowermost floret in each spikelet well developed; paleas rarely with the veins extended as bristles.............................. subsp. brevifolius

2.  One or more of the spikelets at most nodes appearing to have 3 glumes, the lowest 1–2 florets sterile and glumelike; paleas usually with the veins extended as bristles.

3.  Glumes with awns 15–70 mm long, all glumes entire subsp. californicus

3.  Glumes with awns 35–85 mm long, one of the glumes at most nodes with the awn split into 2 or 3 divisions      subsp. elymoides

Elymus elymoides subsp. brevifolius (J.G. Sm.) Barkworth

Longleaf Squirreltail

Culms 25–65(77) cm, erect. Blades usually puberulent abaxially, sometimes glabrous. Spikes 7–20 cm, usually exserted, usually with 2 spikelets per node. Spikelets with (1)2–4(5) florets, lowermost floret functional. Glume awns 50–125 mm, entire; lemma awns 50–120 mm; paleas rarely with the veins extended as bristles.

Elymus elymoides subsp. brevifolius has a wide ecological and elevation range, extending from the arid Sonoran Desert to subalpine habitats, from 600–3500 m. It extends further south than the other subspecies, into northern Mexico , and is rare in Canada .

Elymus elymoides subsp. californicus (J.G. Sm.) Barkworth

California Squirreltail

Culms 8–40 cm, erect or decumbent. Blades usually glabrous abaxially, sometimes puberulent. Spikes 3–10 cm, often partly included, usually with 2 spikelets per node. Spikelets with (1)2–3 fertile florets, lowest 1–2 florets sterile and glumelike. Glume awns 15–40(70) mm, entire; lemma awns 25–70 mm, usually exceeding those of the glumes; paleas often with the veins extending as 1–2 mm bristles.

Elymus elymoides subsp. californicus grows in mid-montane to arctic-alpine habitats in western North America, at elevations of 1500–4200 m. Plants transitional to subsp. elymoides  occur where the two are sympatric.

Elymus elymoides (Raf.) Swezey subsp. elymoides

Common Squirreltail

Culms 15–45 cm, erect to decumbent. Blades usually puberulent abaxially, sometimes glabrous. Spikes 4–15 cm, exserted or partly included, usually with 2 spikelets per node. Spikelets with (1)2–3(4) fertile florets, lowest 1–2 florets sterile and glumelike. Glume awns 35–85 mm, often split into 2, sometimes 3, unequal divisions; lemma awns 25–75 mm, usually exceeded by those of the glumes; paleas with the veins extending as bristles.

Elymus elymoides subsp. elymoides grows in desert and shrub-steppe areas of western North America, extending to the western edge of the Great Plains and, as an adventive, occasionally further east. It is frequently associated with disturbed sites.

Elymus elymoides subsp. hordeoides (Suksd.) Barkworth

Culms 10–20 cm, erect. Blades glabrous or puberulent abaxially. Spikes 3–6 cm, exserted or partly included, with 3 spikelets per node. Spikelets in the central position usually with 2 fertile florets, the lateral spikelets usually with rudimentary to awnlike florets. Glume awns 15–50 mm, usually entire; lemma awns of the fertile florets 15–30 mm; paleas with or without distinct bristles.

Elymus elymoides subsp. hordeoides grows in dry, rocky, often shallow soils, particularly in Artemisia rigida–Poa secunda  communities, from eastern Washington and Idaho to northern California and Nevada. It resembles some Elymus–Hordeum  hybrids.

22.  Elymus trachycaulus (Link) Gould

Plants usually cespitose, sometimes weakly rhizomatous. Culms 30–150 cm, ascending to erect; nodes usually glabrous. Leaves somewhat basally concentrated; sheaths usually glabrous, sometimes markedly retrorsely hirsute or villous; auricles absent or to 1 mm; ligules 0.2–0.8 mm, truncate; blades 2–5(8) mm wide, flat to involute, usually straight and ascending, abaxial surfaces usually smooth and glabrous, sometimes hairy, adaxial surfaces usually glabrous, sometimes conspicuously hairy. Spikes 4–25 cm long, 0.4–1 cm wide, erect, with 1 spikelet at all or most nodes; internodes (4)7–9(12) mm, edges scabrous, both surfaces smooth and glabrous. Spikelets 9–17(20) mm long, usually at least twice as long as the internodes, 3–6 mm wide, appressed, with 3–9 florets, lowest florets functional; rachillas glabrous or hairy, hairs to 0.3 mm; disarticulation above the glumes, beneath each floret. Glumes subequal, 5–17 mm long, from 3/4 as long as to longer than the adjacent lemmas, 1.8–2.3 mm wide, lanceolate to narrowly ovate, widest about midlength, usually green, purple at higher latitudes and elevations, flat or asymmetrically keeled for their full length, 3–7-veined, the keel vein usually scabrous, the others smooth or scabrous, only 1 vein extending to the apex, adaxial surfaces glabrous, margins hyaline or scarious, usually more or less equal, 0.2–0.5 mm wide, widest at or slightly beyond midlength, apices acute to awned, awns to 11 mm; lemmas 6–13 mm, glabrous, usually smooth proximally, often scabridulous distally over the veins, apices acute, usually awned, awns to 40 mm, usually straight, sometimes weakly curved if shorter than 10 mm; paleas subequal to the lemmas, keels straight or slightly outwardly curved below the apices, tapering to the apices, apices truncate, 0.15–0.3 mm wide, keel veins often extending beyond the intercostal region, sometimes forming teeth; anthers (0.8)1.2–2.5(3) mm. 2n = 28. Haplomes StH.

Elymus trachycaulus grows from sea level to 3300 m, usually in open or moderately open areas, but sometimes in forests. Its range extends from the boreal forests of North America east through Canada to Greenland and south into Mexico . It also grows, as an introduction, in Asia and Europe. It exhibits considerable variability in the presence or absence of rhizomes, the length and density of the spike, awn development on the glumes and lemmas, and glume venation. The variability in these features has often been used to circumscribe infraspecific taxa, but most such taxa, even though locally distinctive, appear to intergrade. Some of the features appear to be strongly influenced by environmental factors. For instance, plants growing in forested areas of northwestern North America tend to be slightly rhizomatous, more gracile, and later-flowering that those in adjacent, more exposed areas; whether they constitute a distinct taxon or merely a forest ecotype is not clear. Plants growing at higher elevations tend to have glumes with more widely spaced veins and broader, often unequal margins, resembling E. violaceus  in these respects. Whether this reflects ecotypic differentiation, hybridization with E. violaceus, or greater genetic continuity than is suggested by their placement in different species is not clear.

Jozwik (1966) recognized four groups within E. trachycaulus. Group I comprised unawned or shortly awned specimens; group II a polymorphic assemblage of awned specimens; group III a rather homomorphic group of specimens with secund spikes and relatively long awns; and group IV a relatively homomorphic group of unawned, high-elevation specimens. Jozwik concluded that group II consists of hybrids and backcrosses between E. trachycaulus and other species of Triticeae . He based this conclusion on consideration of field observations, artificial hybrids, the polymorphism of the specimens, and the geographic distribution of the group. This last was similar to that of unawned specimens of E. trachycaulus, but the populations were highly scattered within the area concerned. Jozwik’s group III is treated here as Elymus trachycaulus subsp. subsecundus . His group IV is treated here as E. violaceus .

Elymus trachycaulus is often confused with E. stebbinsii . It differs in having shorter anthers, shorter internodes, and glumes that are sometimes awned. It may also be confused, particularly in the herbarium, with specimens of E. glaucus  having solitary spikelets at all the spike nodes; it usually differs in having shorter anthers and less acuminate glumes. When, as is sometimes the case, the two species grow together, E. trachycaulus can be distinguished by its stiffer leaves. Elymus trachycaulus also resembles E. macrourus  and E. alaskanus , but its glumes are longer relative to the lemmas. It also has less hairy rachillas than most plants of those species.

C.L. Hitchcock et al. (1969) treated Elymus trachycaulus as a subspecies of E. caninus ; it differs consistently from the latter species in glumes that are glabrous on the adaxial (inner) surface, in a chromosome interchange, and in its molecular characteristics (Sun et al. 1998). It also tends to have a more erect spike.

Elymus trachycaulus has been implicated in several interspecific and intergeneric hybrids. Named interspecific hybrids (and the other parent) are E. Χcayouetteorum  (E. canadensis ), E. Χpalmerensis  (E. sibiricus ), E. Χpseudorepens  (E. lanceolatus ), and E. Χsaundersii  (E. elymoides ). Hybrids withE. hystrix  have been named ΧAgroelymus dorei Bowden ; the appropriate combination has not been made in Elymus. Named intergeneric hybrids are ΧElyhordeum macounii  (Hordeum jubatum ), ΧElyleymus jamesensis  (Leymus mollis ), and ΧElyleymus ontariensis  (Leymus innovatus ). Hybrids with Elymus elymoides , E. multisetus , and Hordeum jubatum  have brittle rachises and tend to be awned. Others are harder to recognize.

1.  Lemma awns 17–40 mm long, longer than the lemma body, straight; spikes somewhat 1-sided        subsp. subsecundus

1.  Lemmas unawned or with awns to 24 mm long, shorter or longer than the lemma body, straight or curved; spikes 2-sided.

2.  Lemma awns 9–24 mm long putative hybrids between E. trachycaulus and other species of Triticeae

2.  Lemmas unawned or with awns to 9 mm long, the awns sometimes curved.

3.  Spike internodes 8–15 mm long; spikes 8–25 cm long; glumes unawned or with straight awns to 2 mm long; spikelet bases usually visible; lemmas unawned or with straight awns to 40 mm long       subsp. trachycaulus

3.  Spike internodes 4–5 mm long; spikes 5–10 cm long; glumes awned, awns 1.8–4 mm long; spikelet bases usually concealed; lemmas awned, awns 2–3 mm long, slightly curved subsp. virescens

Elymus trachycaulus subsp. subsecundus (Link) Α. Lφve & D. Lφve

Unilateral Wheatgrass

Culms 40–110 cm. Spikes 7–25 cm, somewhat 1-sided. Spikelets with 3–7 florets, the bases usually visible. Glumes 11–17 mm, long-acuminate or awned, awns to 11 mm; lemmas awned, awns 17–40 mm, longer than the lemma body, straight.

Elymus trachycaulus subsp. subsecundus grows primarily in the Great Plains. It may be confused with solitary-spikeleted plants of E. glaucus , from which it differs in its 1-sided spike and its stiffer, more basally concentrated leaves. Jozwik (1966) suggested that it is composed of derivatives from E. trachycaulus subsp. trachycaulus  Χ Hordeum jubatum  hybrids that are adapted to moist prairies. He noted that the unilateral spike is particularly characteristic of artificial hybrids between the two species, and is uncommon in other hybrids.

Elymus trachycaulus (Link) Gould subsp. trachycaulus

Slender Wheatgrass , Ιlyme ΰ Chaumes Rudes , Agropyre ΰ Chaumes Rudes

Culms 30–150 cm. Spikes (4)8–30 cm long, 0.5–0.8 cm wide, 2-sided; internodes 8–15 mm. Spikelets with 3–9 florets, the bases usually visible. Glumes 5–17 mm, at least 1 vein scabrous to near the base, sometimes all veins scabrous, unawned or with straight awns shorter than 2 mm; lemmas unawned or awned, awns to 5 mm, straight.

Elymus trachycaulus subsp. trachycaulus grows throughout the habitat and range of the species, and exhibits considerably more variation than subsp. subsecundus . Two aspects of the variation that seem particularly worthy of further study are the glume venation, and the spacing of spikelets in the spikes. Plants with glumes having 5–7 well-developed, narrowly spaced veins are restricted to lower elevations and the southern portion of the subspecies range; northern plants and plants at higher elevations generally have 3–5 weakly developed and widely spaced veins. The former glumes resemble those of E. glaucus , with which E. trachycaulus subsp. trachycaulus is often sympatric; the latter, those of E. violaceus . Spikelet spacing also varies considerably. In at least some instances, plants with widely spaced spikelets appear to be associated with more shady habitats.

Elymus trachycaulus subsp. virescens (Lange) Α. Lφve & D. Lφve

Culms 20–80 cm. Spikes 5–10 cm long, 0.5–0.8(1) cm wide, 2-sided; internodes 5–10 mm. Spikelets usually with the bases concealed. Glumes 9.5–13.5 mm, 1 vein scabrous over most of its length, the basal 1/4 usually smooth, the remaining veins scabrous or smooth, awned, awns 1.5–2 mm; lemmas awned, awns 2.5–10 mm, often curved.

Elymus trachycaulus subsp. virescens is restricted to Greenland. It is very consistent in its morphology.

23.  Elymus caninus (L.) L.

Bearded Elymus , Bearded Wheatgrass

Plants cespitose, not strongly rhizomatous. Culms 30–130 cm, erect or geniculate, usually hairy on or below the nodes. Leaves evenly distributed; sheaths glabrous; auricles to 1.5 mm; ligules 0.2–1.5 mm; blades 10–30 cm long, 4–10 mm wide, flat, both surfaces scabrous, adaxial surfaces sometimes with hairs over the veins, hairs to 0.5 mm, veins not prominent, widely spaced. Spikes 5–20 cm long, 0.5–1.5 cm wide including the awns, 5–8 mm wide excluding the awns, erect or arching, with 1 spikelet per node; internodes 4.5–7 mm, edges scabrous or ciliate, both surfaces hairy below the spikelets. Spikelets 10–15(20) mm long, 2–5(7) mm wide, appressed to slightly divergent, with 2–6 florets; rachillas scabridulous or pubescent, often more densely pubescent distally; disarticulation above the glumes, beneath each floret. Glumes equal to unequal, 0.6–1 mm wide, lanceolate to narrowly ovate, usually green, flat or weakly keeled, keels eccentric, adaxial surfaces hairy, hairs often inconspicuous, hyaline margins sometimes widest distally, narrowing abruptly to the acute to acuminate apices; lower glumes 8–11 mm, 3-veined, usually awned, awns to 3 mm; upper glumes 10–13 mm, 3–5-veined, sometimes awn-tipped, awns to 0.3 mm; lemmas 9–13 mm, glabrous, smooth to somewhat scabridulous distally, rounded on the back proximally, awned, awns 7–20 mm, straight or flexuous; paleas subequal to the lemmas, keels finely and densely ciliate over most of their length, straight or slightly outwardly curved, tapering to the apices, apices about 0.2 mm wide; anthers 2–3 mm. 2n = 28. Haplomes StH.

Elymus caninus is native to Eurasia; it is not known to be established in the Flora region. A.S. Hitchcock (1935, 1951) reported that it had been collected on ballast dumps in Portland, Oregon, but the specimens concerned belong to E. ciliaris  and E. tsukushiensis . Elymus caninus differs from E. ciliaris and E. tsukushiensis in having flatter glumes that are longer in relation to the lemmas, and palea keels that are straight or almost straight below the apices. Recent reports of its occurrence in the region reflect C.L. Hitchcock et al.’s (1969) treatment, in which E. caninus and E. trachycaulus  were treated as conspecific subspecies. Because E. caninus is the older name, it is the correct name to use at the specific rank under such a treatment.

The hairs on the inside of the glumes are difficult to see. Nevertheless, this is the single most reliable morphological character for distinguishing Elymus caninus from all other species of Elymus in this treatment. Elymus caninus is most likely to be confused with awned plants of E. trachycaulus. The two species also differ in their molecular characteristics, and in at least one chromosome interchange (Sun et al. 1998).

24.  Elymus violaceus (Hornem.) Feilberg

High Elymus , Ιlyme Latiglume

Plants cespitose, not rhizomatous. Culms 18–75 cm, often decumbent or geniculate; nodes usually glabrous. Sheaths glabrous; auricles about 0.5 mm; ligules 0.5–1 mm, truncate; blades 3–4 mm wide, flat, glabrous or hairy, abaxial surfaces less densely hairy and with shorter hairs than the adaxial surfaces, apices acute. Spikes 5–12 cm long, 0.4–0.7 cm wide excluding the awns, erect, with 1 spikelet per node; internodes 4–5.5 mm, edges ciliate. Spikelets 11–19 mm, appressed, with (3)4–5 florets; rachillas hairy, hairs about 0.4 mm; disarticulation above the glumes, beneath each floret. Glumes 8–12 mm long, 1.2–2 mm wide, about 3/4 as long as to equaling the adjacent lemmas, narrowly ovate to obovate, often purplish, glabrous, sometimes scabrous, flat or equally keeled the full length, keels and other veins usually smooth, sometimes scabrous, 3(5)-veined, adaxial surfaces glabrous, margins usually unequal, the wider margin 0.3–1 mm wide, usually widest in the distal 1/3, apices acute to rounded, often awned, awns to 2 mm; lemmas glabrous or pubescent, hairs flexible, all similar, apices usually awned, awns 0.5–3 mm, straight; paleas subequal to the lemmas, tapering to the apices, apices about 0.4 mm wide; anthers 0.7–1.3 mm. 2n = 28. Haplomes StH.

Elymus violaceus grows in arctic, subalpine, and alpine habitats, on calcareous or dolomitic rocks, from Alaska through arctic Canada to Greenland, and south in the Rocky Mountains to southern New Mexico. In western North America, it forms intermediates with E. scribneri , E. trachycaulus , and E. alaskanus . It is treated here as including E. alaskanus subsp. latiglumis  [ Agropyron latiglume], E. alaskanus being restricted to plants with relatively short glumes that are often found in valleys and at lower elevations than E. violaceus. Western plants of E. violaceous tend to be more glaucous, have shorter spikes and spikelets, and more obovate glumes than plants from Greenland but, until more is known about the extent and genetic basis of the variation in and among E. violaceus, E. alaskanus, and E. trachycaulus, formal taxonomic recognition seems inappropriate.

25.  Elymus macrourus (Turcz. ex Steud.) Tzvelev

Hairy Elymus

Plants cespitose, sometimes appearing weakly rhizomatous. Culms 35–100 cm, ascending to erect; nodes sometimes pubescent. Sheaths glabrous; auricles absent; ligules 0.5–1 mm, truncate to rounded; blades 3–10 mm wide, flat, usually glabrous, abaxial surfaces smooth or scabridulous, adaxial surfaces scabrous. Spikes 5–20 cm long, 0.4–0.8 cm wide, erect, with 1 spikelet per node; internodes 7–8 mm long, about 0.5 mm wide, glabrous below the spikelets. Spikelets 12–20 mm, appressed, with 4–7 florets; rachillas hairy, hairs 0.3–0.5 mm; disarticulation above the glumes, beneath each floret. Glumes 6–10 mm long, 1/3–2/3 the length of the spikelets and to about 1/2 the length of the adjacent lemmas, 0.8–1.8 mm wide, widest at about midlength, lanceolate, flat, rounded, or symmetrically keeled, usually green or green tinged with purple, 3–4-veined, veins scabridulous, scabrous, or with hairs to 0.3 mm, usually glabrous elsewhere, margins subequal, about 0.3 mm wide, widest near midlength, apices acute, unawned or awned, awns to 1 mm; lemmas 8–12 mm, hairy throughout or glabrous distally, hairs all alike, 0.2–0.3 mm, apices unawned or awned, awns to 7 mm, straight; paleas subequal to the lemmas, tapering to the apices, apices about 0.8 mm wide; anthers 1–2 mm. 2n = 28.

Elymus macrourus grows on river banks and bars, lake shores, and hillsides in northwestern North America. Outside of North America, it grows across the Russian arctic, and extends south into the boreal forest. Plants growing in shifting river banks and bars often appear rhizomatous, as the lower internodes elongate in response to the disturbed substrate. Plants of E. macrourus differ from E. alaskanus  in the shape of their glumes and their narrower glume margins, and from E. trachycaulus  in their relatively short glumes and evidently hairy rachilla segments.

Three varieties of Elymus macrourus are recognized in Russian treatments. It is not clear to which, if any, of the Russian species North American plants belong. A circumboreal study is needed, using plants grown from seeds collected in the wild. Seeds available as E. macrourus through germplasm resources appear to be misidentified.

Elymus macrourus is one of the parents in both Elymus Χpalmerensis  and ΧElyhordeum pilosilemma .

26.  Elymus alaskanus (Scribn. & Merr.) Α. Lφve

Plants cespitose or weakly rhizomatous. Culms 20–90 cm, sometimes decumbent at the base, ascending to erect above; nodes usually pubescent, sometimes glabrous. Leaves sometimes basally concentrated; sheaths smooth or scabrous, glabrous or pilose; auricles absent or to 0.5 mm; ligules 0.2–1 mm, erose, ciliolate; blades 3–7 mm wide, flat, both surfaces smooth, scabrous, or pubescent. Spikes 3.5–14 cm long, 0.5–0.8 cm wide, erect or nodding distally, usually with 1 spikelet per node, occasionally with 2 at the lower nodes; internodes 3–10 mm long, 0.5–0.8 mm wide, mostly glabrous and smooth, edges scabrous or ciliate. Spikelets 9–15(20) mm, 2–5 times longer than the internodes, appressed, with 3–6 florets, rachillas hispidulous; disarticulation above the glumes, beneath each floret. Glumes 4–8 mm long, (1.2)1.5–2 mm wide, 1/3–2/3 as long as the as the adjacent lemmas, oblanceolate to obovate, flat, usually purplish, glabrous or hairy, hairs 0.3–0.5 mm, margins unequal, the widest margin 0.4–1 mm wide, both margins widest above the middle, apices unawned or awned, awns to 1 mm; lemmas 7–11 mm, glabrous or hairy, sometimes scabridulous, sometimes more densely hairy distally, hairs 0.2–0.6 mm, all alike, apices unawned or awned, awns to 7 mm, straight; paleas subequal to the lemmas, keels straight below the apices; anthers 1–2 mm. 2n = 28.

Elymus alaskanus extends across the high arctic of North America to extreme eastern Russia . This treatment interprets Elymus alaskanus as having relatively short glumes, in accordance with its treatment by Hultιn (1968). Large specimens resemble E. macrourus , but differ in the shape of their glumes and in their wider glume margins. Elymus alaskanus differs from E. trachycaulus  in its greater cold tolerance and the distal widening of its glume margins. There is some intergradation, particularly with E. violaceus  and E. trachycaulus, but these species have longer glumes. Moreover, in western North America, E. violaceus is restricted to rocky habitats at or above treeline, whereas E. alaskanus is often associated with valleys and flat areas. Reports of its extending to New Mexico are based on the inclusion of high-elevation forms of E. trachycaulus.

1.  Glumes glabrous, scabrous or sparsely hairy, hairs to about 0.2 mm long; lemmas glabrous or with hairs to about 0.2 mm long........................................................................ subsp. alaskanus

1.  Glumes and lemmas densely hairy, hairs 0.2–0.5 mm long subsp. hyperarcticus

Elymus alaskanus (Scribn. & Merr.) Α. Lφve subsp. alaskanus

Alaskan Elymus , Alaskan Wheatgrass

Plants cespitose or shortly rhizomatous. Culms 25–90 cm, sometimes decumbent; nodes often exposed, glabrous or pubescent. Ligules 0.2–0.6 mm; blades 3–7 mm wide. Spikes 3.5–14 cm; internodes scabrous on the edges. Glumes glabrous, scabrous or sparsely hairy, hairs to about 0.2 mm; lemmas glabrous or hairy, sometimes more densely hairy distally, hairs about 0.2 mm, apices unawned or awned, awns to 7 mm, straight.

Elymus alaskanus subsp. alaskanus grows on river banks and hillsides, primarily north of 50° N latitude.

Elymus alaskanus subsp. hyperarcticus (Polunin) Α. Lφve & D. Lφve

High-Arctic Elymus

Plants cespitose, not rhizomatous. Culms 20–35(50) cm, ascending to erect; nodes concealed. Ligules 0.5–1 mm, erose to ciliate; blades 2.5–5 mm wide. Spikes 4.5–7 cm; internodes 4–6 mm, ciliate, distal cilia longest. Glumes densely hairy, hairs 0.2–0.5 mm, apices mucronate or awned, awns to 1 mm; lemmas densely hairy, hairs 0.2–0.5 mm, apices awned, awns 1–5 mm, straight. 2n = 28.

Elymus alaskanus subsp. hyperarcticus grows on river banks and hillsides. It extends from the Lake Taymyr Basin in Arctic Russia across northern North America to Greenland.

27.  Elymus lanceolatus (Scribn. & J.G. Sm.) Gould

Plants strongly rhizomatous, sometimes glaucous. Culms 22–130 cm, erect; nodes glabrous. Leaves often mostly basal, sometimes more evenly distributed; sheaths glabrous or pubescent; auricles usually present on the lower leaves, 0.5–1.5 mm; ligules 0.1–0.5 mm, erose, sometimes ciliolate; blades 1.5–6 mm wide, generally involute, abaxial surfaces usually glabrous, adaxial surfaces strigose, ribs subequal in size and spacing. Spikes 3.5–26 cm long, 0.5–1 cm wide, erect to slightly nodding, usually with 1 spikelet per node, sometimes with 2 at a few nodes; internodes 3.5–15 mm long, 0.1–0.8 mm wide, glabrous or hairy. Spikelets 8–31 mm, 1.5–3 times longer than the internodes, appressed, with 3–11 florets; rachillas glabrous or hairy, hairs to 1 mm; disarticulation above the glumes, beneath each floret. Glumes subequal, 5–14 mm long, 1/2–3/4 the length of the adjacent lemmas, 0.7–1.3 mm wide, lanceolate, glabrous or hairy, smooth or scabrous, 3–5-veined, flat or weakly, often asymmetrically keeled, keels straight, margins narrow, tapering from the base or from beyond midlength, apices acute to acuminate, sometimes mucronate or shortly awned; lemmas 7–12 mm, glabrous or hairy, hairs all alike, sometimes scabrous, acute to awn-tipped, awns to 2 mm, straight; paleas about equal to the lemmas, keels straight below the apices, proximally smooth or scabrous, sometimes hairy, scabrous distally, intercostal region glabrous or with hairs, apices 0.2–0.3 mm wide; anthers (2.5)3–6 mm. 2n = 28.

Elymus lanceolatus grows in sand and clay soils and dry to mesic habitats. It is restricted to Canada and the contiguous United States , growing primarily between the coastal mountains and 95° W longitude, with the exception of E. lanceolatus subsp. psammophilus , which extends around the Great Lakes. Three subspecies are recognized, primarily on the basis of their lemma and palea pubescence.

Elymus lanceolatus is primarily outcrossing, and hybridizes with several species of Triticeae . Elymus albicans  is thought to be derived from hybridization with the awned phase of Pseudoroegneria spicata . Judging from specimens of controlled hybrids, hybridization with E. trachycaulus  and unawned plants of Pseudoroegneria spicata probably occur, but would be almost impossible to detect without careful observation in the field. Experimental hybrids are partially fertile, and capable of backcrossing to either parent (Dewey 1965, 1967, 1968, 1975, 1976).

1.  Lemmas densely hairy, hairs flexible, some 1 mm long or longersubsp. psammophilus

1.  Lemmas glabrous or with stiff hairs shorter than 1 mm.

2.  Lemmas with hairs, not scabrous...... subsp. lanceolatus

2.  Lemmas smooth, sometimes scabrous distally, mostly glabrous, sometimes the lemma margins proximally hairy     subsp. riparius

Elymus lanceolatus (Scribn. & J.G. Sm.) Gould subsp. lanceolatus

Thickspike Wheatgrass

Culms 60–130 cm. Spikes 10–22 cm; internodes 7–15 mm, smooth, scabrous, or hairy distally. Spikelets 10–28 mm. Lemmas not scabrous, moderately hairy, hairs stiff, shorter than 1 mm.

Elymus lanceolatus subsp. lanceolatus grows in clay, sand, loam, and rocky soils, and is widely distributed in the western Flora region. It is most likely to be confused with the octoploid Pascopyrum smithii ; it differs morphologically from that species in having more evenly distributed leaves and acute glumes that tend to taper from midlength or higher, rather than acuminate glumes that tend to taper from below midlength. In addition, the midvein of the glumes of E. lanceolatus is straight, whereas that of Pascopyrum smithii “leans” to the side distally.

Elymus lanceolatus subsp. psammophilus (J.M. Gillett & H. Senn) Α. Lφve

Sand-Dune Wheatgrass

Culms 20–95 cm. Spikes 4–26 cm; internodes 3.5–13 mm, hairy at least distally. Spikelets 9–31 mm. Lemmas densely hairy, hairs flexible, usually many longer than 1 mm; paleas hairy between the keels, keels hairy proximally.

Elymus lanceolatus subsp. psammophilus tends to grow in sandy soils. It was originally described from around the Great Lakes, but plants with similar vestiture have been found scattered throughout the western range of the species, almost always in association with sandy soils. Those from the Yukon and northern British Columbia tend to be shorter and have smaller spikelets and spikelet parts than those from Washington and Saskatoon, but there is considerable overlap in these characters. Plants from around the Great Lakes (Gillett and Senn 1960) were almost completely pollen sterile. Despite this, Gillett and Senn rejected the notion that they were hybrids.

Elymus lanceolatus subsp. riparius (Scribn. & J.G. Sm.) Barkworth

Streambank Wheatgrass

Culms usually 22–60 cm. Spikes 6–10 cm; internodes 3.5–10 mm, glabrous, sometimes scabrous. Spikelets 10–17 mm. Lemmas smooth, sometimes scabrous distally, mostly glabrous, margins sometimes hairy proximally.

Elymus lanceolatus subsp. riparius grows throughout most of the western part of the range of E. lanceolatus, being more common in mesic habitats and clay soils than the other two subspecies.

28.  Elymus stebbinsii Gould

Plants cespitose or shortly rhizomatous. Culms 60–140 cm; nodes glabrous or retrorsely pubescent. Leaves evenly distributed; sheaths glabrous or pubescent; auricles usually present, 0.5–1.2 mm; ligules 0.3–3.5 mm, truncate to acute, sometimes long-ciliate; blades 4–6.5 mm wide, flat or the margins involute, straight. Spikes 15–31 cm long, 0.4–1.5 cm wide including the awns, 0.4–0.8 cm wide excluding the awns, erect, with 1 spikelet per node; internodes 9–27 mm long, 1–1.3 mm wide, glabrous, smooth. Spikelets 13–29 mm long, from shorter than to almost twice as long as the internodes, 2.5–5 mm wide, appressed, with 5–7 florets; rachillas glabrous; disarticulation above the glumes and beneath each floret. Glumes subequal, 7.5–12 mm long, 1.2–1.5 mm wide, rounded on the back, lanceolate, widest at about midlength, flat or rounded on the back, 5-veined, veins smooth, scabrous or just the midvein scabridulous, margins widest at about midlength, apices acute, unawned; lemmas 9–12 mm, glabrous, sometimes scabrous, acute, unawned or awned, awns to 28 mm, straight; paleas subequal to the lemmas, tapering, apices 0.2–0.3 mm wide; anthers (3.5)4–7 mm. 2n = 28.

Elymus stebbinsii is restricted to California, where it grows on dry slopes, chaparral, and wooded areas, at elevations below 1600 m. It differs from other Elymus species primarily in its combination of long anthers and solitary spikelets. It is often confused with solitary-spikelet plants of E. glaucus  and E. trachycaulus . It differs from both in its longer anthers, and from most representatives of E. glaucus in its acute, but unawned, glumes.

1.  Lemmas awned, awns 8–28 mm long; lower leaf sheaths rarely pubescent; spikelets 13–22 mm long               subsp. septentrionalis

1.  Lemmas unawned or with awns to 8(12) mm long; lower leaf sheaths pubescent or glabrous; spikelets 17–29 mm long......................................................................... subsp. stebbinsii

Elymus stebbinsii subsp. septentrionalis Barkworth

Northern Stebbins’ Wheatgrass

Lowest visible cauline node usually glabrous, rarely pubescent. Lower leaf sheaths usually glabrous, rarely pubescent. Spike internodes 9–21 mm. Spikelets 13–22 mm. Lemmas awned, awns 8–28 mm.

Elymus stebbinsii subsp. septentrionalis grows primarily in the Sierra Nevada. Its range extends from near the Oregon border to Tulare County, California, and includes the coastal mountains north of San Francisco Bay.

Elymus stebbinsii Gould subsp. stebbinsii

Stebbins’ Wheatgrass

Lowest visible cauline node often pubescent. Lower leaf sheaths pubescent or glabrous. Spike internodes 16.3–27 mm. Spikelets 17–29 mm. Lemmas unawned or awned, awns to 8(12) mm.

Elymus stebbinsii subsp. stebbinsii is best known from the coastal mountains south of San Jose, California. It also grows at scattered locations from the central Sierra Nevada south to the Transverse Mountains.

29.  Elymus arizonicus (Scribn. & J.G. Sm.) Gould

Arizona Wheatgrass

Plants cespitose, not rhizomatous. Culms 45–100 cm, erect or decumbent at the base; nodes glabrous or almost so. Leaves evenly distributed over the lower 1/2 of the culms; sheaths glabrous; auricles usually present, to 1 mm; ligules to 1 mm on the basal leaves, 1–3 mm on the flag leaves; blades 2.5–6 mm wide, lax, abaxial surfaces smooth and glabrous, adaxial surfaces scabrous, with scattered 0.5–1 mm hairs, veins close together. Spikes 12–25 cm long, 2.5–6 cm wide including the awns, 10–15 mm wide excluding the awns, flexuous, usually nodding or pendent at maturity, with 1 spikelet per node; internodes 11–17 mm long, 0.4–1 mm wide, glabrous, mostly smooth, scabrous on the edges. Spikelets 14–26 mm long, 6–8 mm wide, appressed to divergent, 1.5–2 times as long as the internodes, with 4–6 florets; rachillas glabrous; disarticulation above the glumes and beneath each floret. Glumes narrowly lanceolate, margins about 0.2 mm wide, 3(5)-veined, the bases flat, evidently veined, margins hyaline, widest at about midlength, acute or acuminate, unawned or awned, awns to 4 mm, straight; lower glumes 5–9 mm, upper glumes 8–10 mm; lemmas 8–15 mm, scabrous, rounded on the back, awns 10–25 mm, arcuately diverging; paleas as long as or longer than the lemmas, tapering, apices truncate, about 0.3 mm wide; anthers 3–5 mm. 2n = 28.

Elymus arizonicus grows in moist, rocky soil in mountain canyons of the southwestern United States and northern Mexico . When mature, the drooping spike and solitary spikelets make E. arizonicus easy to identify. Immature specimens, or those mounted so that the spike appears erect, are easily mistaken for Pseudoroegneria spicata , but they have thicker culms and longer ligules, more basal leaves, and wider leaf blades.

30.  Elymus bakeri (E. Nelson) Α. Lφve

Baker’s Wheatgrass

Plants cespitose, not rhizomatous. Culms 30–50 cm tall, 1–2 mm thick, ascending to erect; nodes glabrous. Leaves not basally concentrated; sheaths glabrous; auricles 0.3–0.6 mm; ligules 0.5–1 mm; blades 12–20 cm long, 2–4 mm wide, stiff, abaxial surfaces smooth, glabrous, adaxial surfaces smooth or scabridulous, veins prominent, closely spaced. Spikes 8–12 cm long, 4–6 cm wide including the awns, about 1 cm wide excluding the awns, straight, erect or inclined, with 1 spikelet per node; internodes 5–9 mm long, about 0.8 mm wide, both surfaces glabrous, edges ciliate. Spikelets 10–19 mm long, about twice as long as the adjacent internodes, 4–10 mm wide, appressed, with 4–5 florets; rachillas scabrous or hirtellous; disarticulation above the glumes, beneath each floret. Glumes 7–12 mm long, 1.4–2 mm wide, narrowly oblong, usually green or green tinged with purple, the bases evidently veined or indurate for less than 0.5 mm, 5-veined, veins scabrous, margins narrow, widest distally, apices acute, sometimes bifid, awned, awns 2–8 mm, straight or divergent; lemmas scabrous or smooth, apices often shortly bidentate, awns 10–35 mm, arcuate to recurved; paleas equaling or slightly longer than the lemmas, tapering to the 0.2–0.4 mm wide apices; anthers 0.8–1.5 mm. 2n = 28.

Elymus bakeri grows in high, but not alpine, mountain meadows of Montana, Utah, Colorado, and northern New Mexico. It resembles the awned phase of Pseudoroegneria spicata , but differs in having rather thicker culms and spikes, and stouter lemma awns. W.A. Weber (University of Colorado, pers. comm., ca. 1999) stated that it often forms large stands in Colorado.

Reports of Elymus bakeri from Idaho appear to be based on fertile hybrids of Elymus trachycaulus  or E. violaceus  with Pseudoroegneria spicata ; that for Wallowa County, Oregon on a specimen of E. glaucus .

31.  Elymus scribneri (Vasey) M.E. Jones

Scribner’s Wheatgrass

Plants cespitose, not rhizomatous. Culms 15–35(55) cm, prostrate to strongly decumbent, at least at the base; nodes glabrous. Sheaths glabrous or shortly pilose; auricles usually present, 0.5–1 mm; ligules 0.2–0.4(0.7) mm, usually truncate, occasionally acute, entire to erose; blades 1.5–4 mm wide, usually involute, adaxial surfaces prominently ribbed. Spikes 3.5–10 cm long, 0.8–1.2 cm wide excluding the awns, 3–6 cm wide including the awns, usually with 1 spikelet per node, occasionally with 2 spikelets at the lower nodes; internodes 2.5–5(7) mm long, 0.5–1 mm wide, glabrous, mostly smooth, edges scabrous. Spikelets 9–15 mm long, 6–12 mm wide, appressed to ascending, with 3–6 florets; rachilla internodes 0.8–1.3 mm, scabridulous; disarticulation initially at the rachis nodes, subsequently beneath each floret. Glumes 4–9 mm long, 0.5–1 mm wide, mostly glabrous, midveins scabrous, 3–5-veined, entire, tapering into a divergent, 12–30 mm awn; lemmas 7–10 mm, usually glabrous, occasionally scabridulous, awned, awns 15–30 mm, divergent, scabridulous; paleas usually longer than the lemmas, apices ciliate, truncate or the veins extending into teeth, teeth about 0.5 mm; anthers 1–1.6 mm. 2n = 28.

Elymus scribneri grows in rocky areas in open subalpine and alpine regions, at 2500–3200 m, often in windswept locations, in southwestern Alberta and the western United States . It is often confused with E. elymoides , but differs from that species in having only one spikelet per node, wider glumes, and more tardily disarticulating rachises. It also resembles E. sierrae , from which it differs in its disarticulating rachises, denser spikes, and shorter anthers.

Several taxonomists have suggested that Elymus scribneri consists of fertile hybrids between E. violaceus  and E. elymoides . This suggestion is supported by the frequency with which the three taxa are sympatric, the morphological variation exhibited by E. scribneri, and cytogenetic data (Dewey 1967).

32.  Elymus sierrae Gould

Sierra Wheatgrass

Plants cespitose, not rhizomatous. Culms 20–50 cm, prostrate or decumbent and geniculate; nodes 1–2, exposed, glabrous. Leaves basally concentrated; sheaths glabrous; auricles usually present, to 1 mm on the lower leaves; ligules 0.2–0.5 mm, erose; blades 1–5 mm wide, flat, abaxial surfaces smooth, glabrous, adaxial surfaces prominently ridged over the veins, with scattered hairs, hairs to 0.2 mm, veins closely spaced. Spikes 5–15 cm long, 1.5–2.5 cm wide including the awns, 0.7–1.2 cm wide excluding the awns, flexuous, erect to nodding distally, with 1 spikelet at most nodes, occasionally some of the lower nodes with 2 spikelets; internodes 5–15 mm long, 0.2–0.5 mm wide, both surfaces glabrous, edges ciliate, not scabrous. Spikelets 15–20 mm, ascending to divergent, with 3–7 florets, rachillas glabrous; disarticulation above the glumes, beneath each floret. Glumes subequal, 6–9 mm long, 0.7–1 mm wide, lanceolate, glabrous, the bases evidently veined, apices entire, tapering into a 3–10 mm awn; lemmas 12–16 mm, glabrous, sometimes scabridulous, apices bidentate, awned, awns 15–30 mm, arcuately diverging to strongly recurved; paleas subequal to the lemmas, apices about 0.4 mm wide; anthers 2–3.5 mm. 2n = 28.

Elymus sierrae is best known from rocky slopes and ridge tops in the Sierra Nevadas, at 2130–3375 m, and is also found in Washington and Oregon. It resembles E. scribneri , differing in its non-disarticulating rachises, longer rachis internodes, and longer anthers. Hybrids with E. elymoides  have glumes with awns 15+ mm long, and some spikelets with narrower glume bases and shorter anthers. Specimens with wide-margined glumes suggest hybridization with E. violaceus .

33.  Elymus wawawaiensis J.R. Carlson & Barkworth

Snakeriver Wheatgrass

Plants cespitose, sometimes weakly rhizomatous. Culms (15)50–130 cm, erect, mostly glabrous; nodes usually glabrous, sometimes slightly pubescent. Leaves more or less evenly distributed; basal sheaths glabrate, margins not evidently ciliate; auricles absent or to 1.2 mm; ligules 0.1–1.1 mm; blades to 28 cm long, 1.7–5 mm wide, involute when dry, adaxial surfaces usually densely pubescent, rarely sparsely pubescent. Spikes 5–20 cm long, 2.5–3 cm wide including the awns, erect to slightly nodding, with 1 spikelet per node; internodes 5–12 mm long, about 0.2 mm thick, about 0.3 mm wide, glabrous beneath the spikelets. Spikelets 10–22 mm long, about twice as long as the internodes, 2–8.5 mm wide, appressed, with 4–10 florets; rachillas glabrous; disarticulation above the glumes, beneath each floret. Glumes 4–10 mm long, 0.5–1.3 mm wide, narrowly lanceolate, widest at or below midlength, glabrous, often glaucous, 1–3-veined, flat or weakly keeled, margins 0.1–0.2 mm wide, widest near midlength, apices usually acuminate, awned or unawned, awns to 6 mm; lemmas 6–12 mm, smooth or slightly scabrous, margins often sparsely pubescent proximally, awned, longest awns in the spikelets 9–28 mm, strongly divergent; paleas 7.2–10.5 mm, keels scabrous distally, tapering to the 0.2–0.3 mm wide apices; anthers 3.5–6 mm. 2n = 28.

Elymus wawawaiensis grows primarily in shallow, rocky soils of slopes in coulees and reaches of the Salmon, Snake, and Yakima rivers of Washington, northern Oregon, and Idaho. There are also a few records from localities at some distance from the Snake River and its tributaries. These probably reflect deliberate introductions. C.V. Piper, who worked for the U.S. Department of Agriculture in southeastern Washington from 1892–1902, frequently distributed seed from populations that he considered superior to farmers in the region; he considered E. wawawaiensis to be a superior form of what is here called Pseudoroegneria spicata . Another source of introduced populations is ‘Secar’, a cultivar of E. wawawaiensis that is recommended as a forage grass for arid areas of the northwestern United States .

Elymus wawawaiensis resembles a vigorous version of Pseudoroegneria spicata, and was long confused with that species. It differs in its more imbricate spikelets and narrower, stiff glumes. In its primary range, E. wawawaiensis is often sympatric with P. spicata, but the two tend to grow in different habitats, E. wawawaiensis growing in shallow, rocky soils and P. spicata in medium- to fine-textured loess soil. The two species also differ cytologically, E. wawawaiensis being an allotetraploid, and P. spicata consisting of diploids and autotetraploids.

34.  Elymus albicans (Scribn. & J.G. Sm.) Α. Lφve

Montana Wheatgrass

Plants strongly rhizomatous. Culms 40–100 cm, erect or decumbent only at the base, glabrous. Leaves somewhat basally concentrated; sheaths glabrous; auricles usually present, to 0.8 mm; ligules 0.2–0.5 mm, ciliolate; blades 1–3 mm wide, usually involute, adaxial surfaces scabrous to strigose. Spikes 4–14 cm long, 1.5–2.5 cm wide including the awns, 0.3–0.8 cm wide excluding the awns, erect, with 1 spikelet per node; internodes 6–14 mm long, 0.2–0.4 mm wide, glabrous or pubescent beneath the spikelets. Spikelets 10–18 mm, 1.5–2 times longer than the internodes, appressed to ascending, with 3–7 florets; rachillas strigillose; disarticulation above the glumes, beneath each floret. Glumes subequal, 1/2 as long as to almost equaling the adjacent lemmas, glabrous or hairy, weakly keeled, keels and adjacent veins smooth to evenly and strongly scabrous from the base to the apices, margins 0.2–0.3 mm wide, apices acute, acuminate, or shortly awned; lower glumes 4–8 mm; upper glumes 4.5–8 mm; lemmas 7.5–9.5 mm, glabrous or densely hairy, awns 4–12 mm, at least some strongly divergent; paleas subequal to the lemmas, tapering to the 0.1–0.3 mm wide apices; anthers 3–5 mm. 2n = 28.

Elymus albicans grows primarily in the central Rocky Mountains and the western portion of the Great Plains. It tends to grow in shallow, rocky soils on wooded or sagebrush-covered slopes, rather than in deep loams. It is derived from hybrids between Pseudoroegneria spicata  and E. lanceolatus . In practice, it is probably restricted to hybrids involving the awned variant of Pseudoroegneria spicata, because the hybrid origin of those involving the unawned variant would probably not be recognized.

Populations of E. albicans differ in their reproductive abilities (Dewey 1970). In some, most plants yield good seed; in others, most plants are sterile. Some of the fertile populations appear to be self-perpetuating; others appear to consist of recent hybrids and some backcrosses. Although treated here as a species, E. albicans could equally well be treated as a hybrid, Elymus Χalbicans. Plants with glabrous lemmas, presumed to be derived from crosses with glabrous individuals of E. lanceolatus, have sometimes been treated as a distinct taxon, e.g., Agropyron albicans var. griffithsii (Scribn. & J.G. Sm.) Beetle  or A. griffithsii Scribn. & J.G. Sm. ; they are not formally recognized here.

35.  Elymus repens (L.) Gould

Quackgrass , Couchgrass , Chiendent , Chiendent Rampant

Plants strongly rhizomatous, sometimes glaucous. Culms 50–100 cm. Leaves sometimes somewhat basally concentrated; sheaths pilose or glabrous proximally; auricles 0.3–1 mm; ligules 0.25–1.5 mm; blades 6–10 mm wide, usually flat, abaxial surfaces glabrous or sparsely pilose, adaxial surfaces usually sparsely pilose over the veins, sometimes glabrous, veins smooth, widely spaced, primary veins prominent, separated by the secondary veins. Spikes 5–15 cm long, 0.5–1.5 cm wide, erect, usually with 1 spikelet per node, occasionally with 2 at a few nodes; internodes 4–6(9.5) mm long, 0.5–1.2 mm wide, smooth or scabrous, glabrous, evenly puberulent, or sparsely pilose, hairs to 0.3 mm. Spikelets 10–27 mm, appressed to ascending, with 4–7 florets; disarticulation tardy, usually below the glumes, the spikelets falling intact. Glumes oblong, glabrous, keeled distally, keels inconspicuous and smooth proximally, scabrous and conspicuous distally, lateral veins inconspicuous, hyaline margins present in the distal 1/2, apices acute, unawned or awned, awns to 3 mm; lower glumes 8.8–11.4 mm, 3–6-veined; upper glumes 7–12 mm, 5–7-veined; lemmas 8–12 mm, glabrous, mostly smooth, sometimes scabridulous distally, unawned or with a 0.2–4(10) mm awn, awns straight; paleas 7–9.5 mm, keels ciliate from 1/2 to almost the entire length, apices emarginate, truncate, or rounded; anthers 4–7 mm. 2n = 22, 42. Genome StStH.

Elymus repens is native to Eurasia; it is now established through much of the Flora region, extending from Alaska to Greenland and south to California, Texas, and North Carolina. It grows well in disturbed sites, spreading rapidly via its long rhizomes, as well as by seed. It is also drought tolerant. Although it is listed a noxious weed in several states, it provides good forage. It differs from E. hoffmannii  in having widely spaced, unequally prominent leaf veins and, usually, shorter awns.

Godley (1947) demonstrated that lemma awn development, glaucousness, and the pubescence of the rachises are each effectively controlled by single genes. Long-awned plants are homozygous recessive, and awn-tipped plants homozygous dominant; glaucousness is dominant over non-glaucousness, and glabrous rachises over pubescent rachises. Awned plants appear to be established along the coasts of Newfoundland and Nova Scotia. They have generally been identified as Agropyron pungens (Pers.) Roem. & Schult. , a species that has obtuse, mucronate lemmas.

Elymus repens is almost always a hexaploid. Most studies indicate that its genomic constitution is StStH, but Mason-Gamer (2001) demonstrated that it is genetically more complex than is implied by such a simple formula.

Green portion modified 11 Nov 2010 based on observation and discussion.

36.  Elymus hoffmannii K.B. Jensen & Asay

Hoffmann’s Elymus .

Plants slightly to moderately rhizomatous. Culms 54–135 cm, glabrous. Leaves evenly distributed; sheaths glabrous; auricles absent or to 1 mm; ligules 0.6–1 mm, truncate, erose; blades 5–13 mm wide, flat to involute, abaxial surfaces smooth, glabrous, adaxial surfaces glabrous, veins closely spaced, all more or less equally prominent, smooth or scabrous. Spikes 10–50 cm long, 0.8–1.8 cm wide, with 1 spikelet per node, glabrous below the spikelets; internodes 5–8 mm long, about 0.2 mm thick, about 0.3 mm wide, both surfaces hairy, hairs 0.2–0.4 mm. Spikelets 15–27 mm, appressed to ascending, with 5–7 florets; rachillas scabridulous; disarticulation above the glumes, beneath the florets. Glumes equal, 5–11 mm long, 1.3–1.8 mm wide, stiff, lanceolate to linear-lanceolate, strongly rounded to keeled distally, keels inconspicuous and smooth on the proximal 1/3–1/2, conspicuous and with a few teeth distally, lateral veins inconspicuous, hyaline margins 0.1–0.2 mm wide, apices acuminate to awned, awns to 8 mm; lemmas 7–12 mm, glabrous, smooth, apices unawned or awned, awns to 12 mm, straight; paleas ciliate on the keels, apices about 0.6 mm wide; anthers 4–7 mm. 2n = 42. Genome StStH.

Elymus hoffmannii was described from a breeding line of plants developed from seeds collected in Erzurum Province, Turkey by J.A. Hoffmann and R.J. Metzger (Jensen & Asay 1996). There is no information available about its native distribution. As indicated in the key, E. hoffmannii differs from E. repens  primarily in its evenly prominent, closely spaced leaf veins and, usually, in having longer awns.

The description of Elymus hoffmannii was explicitly written to encompass the cultivar ‘NewHy’. Nevertheless, the cultivar should be identified as ΧPseudelymus ‘NewHy’, because it is derived from an artificial cross between E. repens and Pseudoroegneria spicata . Because of its morphological similarity to plants obtained from the Turkish seed, Jensen and Asay suggested that E. hoffmannii had a similar parentage. ‘NewHy’ was released as a cultivar in the 1980s. Its distribution within the Flora region is not known.

37.  Elymus tsukushiensis Honda

Plants loosely cespitose, without conspicuous rhizomes. Culms 25–100 cm tall, 1.3–3.5 mm thick, erect; nodes 4–6, glabrous. Leaves basal and cauline; sheaths glaucous, glabrous or with hairs, margins glabrous or ciliate distally; auricles 1–2 mm; ligules 0.2–0.7 mm, truncate; blades 3–10 mm wide, flattish, often glaucous. Spikes (6.5)10–25 cm long, 1.4–4 cm wide including the awns, 0.7–20 cm wide excluding the awns, flexuous, nodding; rachises densely to sparsely hirsute on the edges, with about 0.2 mm hairs, glabrous elsewhere, glaucous; internodes (5)8–20 mm. Spikelets 15–25 mm, loosely appressed or ascending, with 5–10 florets; rachillas hairy, hairs about 0.1 mm; disarticulation above the glumes, beneath the florets. Glumes lanceolate, tapering from about midlength, adaxial surfaces glabrous, hyaline margins about 0.1 mm wide, strongly keeled distally, midvein scabrous distally, other veins smooth or scabrous, apices acute to acuminate, sometimes awned, awns 2–5 mm; lower glumes 4–7 mm, 3–5-veined; upper glumes 5–8 mm, 5-veined; calluses glabrous; lemmas 8–12 mm, lanceolate, glabrous or pilose, apices acute, awned, awns 20–40 mm, straight or flexuous; paleas from slightly shorter to longer than the lemmas, keels narrowly winged distally, not or scarcely extending beyond the intercostal region, distinctly outwardly curved below the apices, apices 0.3–0.5 mm wide; anthers 1.5–2.5 mm. 2n = 42. Genome StYH.

Elymus tsuskushiensis is native to northeastern China , Japan , and Korea . It was collected from ballast dumps in Portland, Oregon, but is not established in the Flora region. Hitchcock (1951) identified it and E. ciliaris  as Agropyron caninum (L.) P. Beauv.  [ Elymus caninus ], but that species has flatter glumes that are longer in relation to the lemmas than those of E. tsuskushiensis, and paleas with straight or slightly outwardly curved keels.

38.  Elymus ciliaris (Trin.) Tzvelev

Plants loosely cespitose, without conspicuous rhizomes. Culms 30–130 cm tall, 1–5 mm thick, erect or weakly decumbent; nodes 3–4, glabrous, glaucous. Leaves basal and cauline; sheaths glaucous, glabrous or with hairs, lower sheaths sometimes hairy, upper sheaths glabrous, margins sometimes ciliate; auricles 1.5–2.5 mm; ligules about 0.3 mm; blades 10–25 cm long, 3–10 mm wide, glabrous or pilose. Spikes 10–22 cm long, 1.5–2.5 cm wide including the awns, 0.8–1 cm wide excluding the awns, inclined to nodding, with 1 spikelet at all or most nodes; rachises scabrous on the edges, glabrous below the spikelets; internodes 10–25 mm. Spikelets 5–22 mm long, about 5 mm wide, appressed, with 4–12 florets; disarticulation above the glumes, beneath the florets. Glumes narrowly elliptic to lance-oblong, apices acute to acuminate; lower glumes 5–11 mm; upper glumes 7–13 mm; lemmas 7–12 mm, mostly glabrous, glabrate, or sparsely hairy, margins with coarse stiff hairs, hairs to 1 mm, apices abruptly narrowed, awned, awns 10–20 mm, scabrous, strongly outcurved to recurved; paleas 2/3–4/5 the length of the lemmas, keels winged distally, distinctly outwardly curved below the apices, apices 0.5–0.6 mm wide, truncate to rounded; anthers about 2 mm. 2n = 28. Genome StY.

Elymus ciliaris is native to northern China and Japan . It was collected from ballast dumps in Portland, Oregon, in 1899 and 1902; it is not established in the Flora region. A.S. Hitchcock identified both specimens on the sheet ( US 1017954) as Agropyron caninum (L.) P. Beauv.  [ Elymus caninus ], from which E. ciliaris differs in its short, rounded paleas and relatively short glumes with distinctly outwardly curving keels. The other specimen on that sheet is E. tsuskushiensis .

39.  Elymus semicostatus (Nees ex Steud.) Melderis

Plants cespitose, not rhizomatous. Culms 45–135 cm, erect or geniculately ascending, glabrous. Sheaths glabrous or villous; auricles to 1.5 mm; ligules 0.5–1.5 mm, truncate; blades 15–30 cm long, 4–12 mm wide, sometimes villous, adaxial surfaces smooth or scabrous, primary and secondary veins alternating. Spikes 8–30 cm long, 1–2 cm wide including the awns, 0.5–1 cm wide excluding the awns, erect or nodding, usually with 1 spikelet per node, sometimes with 2 spikelets at the lower nodes; internodes 10–20 mm long, about 0.8 mm wide, scabrous on the margins and on the surfaces, marginal prickles larger than those on the surfaces, hirtellous just below the spikelets. Spikelets 16–30 mm, loosely appressed, with 6–8 florets; rachilla internodes about 0.8 mm, strigose, hairs to about 0.3 mm; disarticulation above the glumes, beneath each floret. Glumes subequal, 10–18 mm long, 1.1–2 mm wide, elliptic-lanceolate, green, not keeled, 5–7-veined, veins more or less equally prominent, scabrous, apices acute to acuminate; lemmas 10–14 mm, scabrous or puberulent dorsally, awned, awns (4)12–18 mm, straight; paleas 3/4 as long as to slightly shorter than the lemmas, keels outwardly curved below the apices, apices 0.3–0.7 mm wide, truncate; anthers 3–6 mm. 2n = 28. Genome StY.

Elymus semicostatus is native to central Asia, from Afghanistan through Pakistan to northeastern India ( Sikkim ). Reports of its presence in the Flora region appear to be based on misidentifications.

Named hybrids

Elymus is notorious for its ability to hybridize. Most of its interspecific hybrids are partially fertile, permitting introgression between the parents. The descriptions provided below are restricted to the named interspecific hybrids. They should be treated with caution and some skepticism; some are based solely on the type specimen, because little other reliably identified material was available. Moreover, as the descriptions of the non-hybrid species indicate, many other interspecific hybrids exist.

The parentage of all hybrids is best determined in the field. Perennial hybrids, such as those in Elymus, can persist in an area after one or both parents have died out, but the simplest assumption is that both are present. Interspecific hybrids of Elymus that have disarticulating rachises presumably have E. elymoides  or E. multisetus  as one of their parents.

40.  Elymus Χcayouetteorum (Boivin) Barkworth

Plants probably cespitose, not rhizomatous. Culms to 1 m tall, about 4 mm thick. Leaves not basally concentrated; sheaths smooth; ligules about 0.5 mm, glabrous; blades 20–30 cm long, about 10 mm wide, both surfaces scabrous. Spikes about 25 cm, lower nodes with 1 spikelet, most middle to upper nodes with 2; internodes about 18 mm. Spikelets about 40 mm including the awns, about 20 mm excluding the awns, appressed, with 5–8 florets. Glumes 12–15 mm, not or scarcely indurate, mostly smooth, veins scabrous, awns 3–5 mm; lemmas about 14 mm, glabrous, awns 18–22 mm, not to moderately divergent; anthers 1.8–2 mm, indehiscent.

Elymus Χcayouetteorum consists of hybrids between Elymus trachycaulus  and E. canadensis . The above description is based on the type specimen, which was collected on the Ilets-ΰ-Jιremie, Quebec. It is not known how widespread such hybrids are.

41. Elymus Χpalmerensis (Lepage) Barkworth & D.R. Dewey

Plants densely cespitose, shortly rhizomatous. Blades (2)4–8(15) mm wide, abaxial surfaces scabrous, adaxial surfaces pilose. Spikes 14–30 cm long, 1–2.5 cm wide including the awns, 0.3–0.8(1.5) cm wide excluding the awns, drooping, with 1–2 spikelets per node; internodes 5–20 mm, scabrous on the angles. Spikelets with 3–9 florets. Glumes 4–10.5 mm long, 0.8–1.5 mm wide, oblong to lanceolate, scabrous, gradually or abruptly narrowing in the distal 1/3–1/4, 3(4)-veined, margins scarious, apices unawned or awned, awns to 15 mm; rachillas hairy; lemmas 8.5–15 mm, hairy, conspicuously keeled distally, awned, awns 3–10 mm; paleas 8.5–15 mm, retuse or truncate; anthers 1–2 mm.

Elymus Χpalmerensis is the name for hybrids between Elymus macrourus  and E. sibiricus . It is known from disturbed sites around Palmer, Alaska, and in southcentral Alaska. Bowden (1967) also reported it from Fort Liard, in the MacKenzie District, Northwest Territories. Lepage (1952) originally identified the parents as Agropyron sericeum  [= Elymus macrourus] and E. canadensis . Later, Lepage (1965) stated that the second parent was E. sibiricus. The above description includes ΧAgroelymus hodgsonii Lepage , which, according to Bowden (1967), is a synonym.

42.  Elymus Χpseudorepens (Scribn. & J.G. Sm.) Barkworth & D.R. Dewey

False Quackgrass

Plants rhizomatous. Culms 30–100 cm, ascending or erect, glabrous, mostly smooth, sometimes scabrous below the nodes. Leaves evenly distributed; sheaths glabrous; ligules to 0.5 mm; blades 10–25 cm long, 2–7 mm wide, involute when dry, both surfaces scabrous, adaxial surfaces sparsely pilose, hairs 0.7–1 mm. Spikes 5.5–13 cm long, 0.4–0.6 cm wide, with 1 spikelet per node; internodes 3.5–5 mm. Glumes 8–18 mm, equaling or exceeded by the adjacent lemmas, more or less flat, 5–9-veined, margins unequal, the wider margins to about 0.3 mm, narrowly acute, sometimes awned, awns to 1 mm; lemmas 7.5–15 mm, smooth and glabrous proximally, scabrous distally, mucronate or awned, awns to 3 mm; anthers 1.5–2 mm.

Elymus Χpseudorepens consists of hybrids between E. lanceolatus  and E. trachycaulus . It appears to be fairly common, having been reported from Alberta to Michigan and south to Arizona, New Mexico, and Arkansas.

43.  Elymus Χyukonensis (Scribn. & Merr.) Α. Lφve

Plants rhizomatous. Culms about 60 cm, erect. Leaves somewhat basally concentrated; blades 3.5–6 mm wide. Spikes 6–10 cm long, 0.7–1.7 cm wide, with 1 spikelet per node; internodes 6–11 mm. Glumes 4–5.5 mm, about 1/2 the length of the adjacent lemmas, lanceolate, flat, hairy, apices acute or awn-tipped, awns shorter than 1 mm; rachillas densely hairy; lemmas 6–9 mm, densely villous, unawned; anthers 3.3–3.6 mm.

The parents of E. Χyukonensis have not been identified. Morphological and geographic considerations suggest that they may be E. lanceolatus subsp. psammophilus  and E. alaskanus .

44.  Elymus Χsaundersii Vasey

Plants cespitose, not rhizomatous. Culms 50–80 cm, erect, glabrous or pilose. Leaves somewhat basally concentrated; sheaths retrorsely hairy; auricles to 1 mm; ligules 0.5–1 mm; blades 10–15 cm long, 4–5 mm wide, flat, becoming involute when dry, tapering to the apices. Spikes 10–25 cm long, 1–2.5 cm wide, with 1 spikelet per node; internodes 4–5 mm; disarticulation at the rachis nodes. Spikelets 10–25 mm excluding the awns, with 3–6 florets. Glumes 6–8 mm, linear-lanceolate to lanceolate, 3–5-veined, veins scabrous, apices sometimes toothed, awned, awns 8–13 mm; lemmas 10–13 mm, glabrous, smooth proximally, scabrous distally, awned, awns 20–45 mm, outcurving; anthers 1.5–2 mm, usually indehiscent.

Elymus Χsaundersii comprises hybrids between E. trachycaulus  and E. elymoides . Such hybrids are found throughout much of the western portion of the contiguous United States , mostly in disturbed areas. The hybrids are generally sterile and, like all hybrids involving E. elymoides or E. multisetus , the rachises disarticulate at maturity.

45.  Elymus Χhansenii Scribn.

Plants cespitose, not rhizomatous. Culms 60–120 cm. Leaves evenly distributed; sheaths smooth; ligules to 1 mm; blades 10–30 cm long, 2–8 mm wide, flat or the margins involute. Spikes 5–20 cm, straight or nodding, with 2+ spikelets per node; internodes about 10 mm; disarticulation in the rachises. Spikelets about 15 mm, with 3–5 florets. Glumes narrowly lanceolate, 2–3-veined, awned, awns 25–35 mm; lemmas 10–12 mm, awned, awns 40–50 mm, outcurving; paleas subequal to the lemmas, truncate or bidentate.

Elymus Χhansenii refers to hybrids between E. glaucus  and either E. elymoides  or E. multisetus . It is not clear which of the latter two species is involved. It is a fairly common hybrid in those parts of western North America where both parents grow. The glumes of the type specimen are as wide as those in E. glaucus, and some are divided longitudinally, as in E. elymoides and E. multisetus. As in other hybrids involving E. elymoides and E. multisetus, the rachis of E. Χhansenii disarticulates at maturity.

46.  Elymus Χpinalenoensis (Pyrah) Barkworth & D.R. Dewey

Plants cespitose, not rhizomatous. Culms 60–90 cm tall, about 2 mm thick. Leaves somewhat basally concentrated; sheaths smooth or scabridulous; auricles to 1.5 mm; ligules 0.5–0.7 mm, rounded; blades 2–2.5 mm wide, those of the basal leaves 7–15 cm long, those of the flag leaves 2–7 cm long, abaxial surfaces smooth or scabridulous, glabrous or sparsely hairy basally, veins not evident, adaxial surfaces scabrous, sometimes with scattered hairs, veins prominently and equally ribbed. Spikes 8–14 cm long, about 5 cm wide including the awns, about 1 cm wide excluding the awns, nodding, lower nodes with 1–2 spikelets, upper nodes with 1 spikelet; internodes about 10 mm; disarticulation in the rachises and beneath each floret. Glumes 22–31 mm including the awns, glume bodies 5–10 mm, midvein evident, scabrous, awns 17–26 mm, divergent, scabrous; lemmas 11–13 mm, smooth, awns 20–40 mm, divergent, sometimes strongly divergent; anthers about 2 mm long, 1–1.5 mm thick.

Elymus Χpinalenoensis consists of hybrids between Elymus elymoides subsp. brevifolius  and E. arizonicus  (Pyrah 1983). It has been found in the Pinaleno and Santa Catalina mountains of Graham County, Arizona, in areas disturbed by logging, road building, summer home development, and recreation.

47.  Elymus Χebingeri G.C. Tucker

Plants cespitose, not rhizomatous. Culms 50–135 cm, usually smooth, glabrous, sometimes retrorsely hairy; nodes glabrous or hairy. Leaves evenly distributed; sheaths smooth or scabridulous, hairy; ligules to 1 mm; blades 14–26 cm long, to 12 mm wide, flat, both surfaces scabridulous, adaxial surfaces hairy. Spikes 8–17 cm, with (1)2+ spikelets per node; internodes 4–8 mm. Spikelets diverging at about 45° from the rachises, not patent. Glumes usually subequal, 15–20 mm, bases indurate, bodies lanceolate to subulate, scabrous, sometimes the lower glumes reduced to a stub; lemmas 8–10 mm, glabrous or strigose, sometimes scabrous, awns 23–29 mm, straight, scabrous; anthers 2–2.9 mm. Caryopses seldom formed.

Elymus Χebingeri is the name for hybrids between E. virginicus  and E. hystrix . It is frequently found, often with later hybrid generations and introgressants to the two parents, where the two parental species grow together. It has been reported from southern Ontario, and from Wisconsin to New York and Illinois. Most published reports simply refer to the existence of these hybrids, the name itself not having been published until 1996.