17.33   MUHLENBERGIA Schreb.
Paul M. Peterson

Plants annual or perennial; usually rhizomatous, often cespitose, sometimes mat-forming, rarely stoloniferous. Culms 2-300 cm, erect, geniculate, or decumbent, usually herbaceous, sometimes becoming woody. Sheaths open; ligules membranous or hyaline (rarely firm or coriaceous), acuminate to truncate, sometimes minutely ciliolate, sometimes with lateral lobes longer than the central portion; blades narrow, flat, folded, or involute, sometimes arcuate. Inflorescences terminal, sometimes also axillary, open to contracted or spikelike panicles; disarticulation usually above the glumes, occasionally below the pedicels. Spikelets with 1(2-3) florets. Glumes usually (0)1(2-3)-veined, apices entire, erose, or toothed, truncate to acuminate, sometimes mucronate or awned; lower glumes sometimes rudimentary or absent, occasionally bifid; upper glumes shorter than to longer than the florets; calluses poorly developed, glabrous or with hairs; lemmas glabrous, scabrous, or with short hairs, 3-veined (occasionally appearing 5-veined), apices awned, mucronate, or unawned; awns, if present, straight, flexuous, sinuous, or curled, sometimes borne between 2 minute teeth; paleas shorter than or equal to the lemmas, 2-veined; anthers (1-2)3, purple, orange, yellow, or olivaceous. Caryopses elongate, fusiform or elliptic, slightly dorsally compressed. Cleistogamous panicles sometimes present in the axils of the lower cauline leaves, enclosed by a tightly rolled, somewhat indurate sheath. x = 10. Named for Gotthilf Henry Ernest Muhlenberg (1753-1815), a Lutheran minister and pioneer botanist of Pennsylvania.

Muhlenbergia is primarily a genus of the Western Hemisphere. It has approximately 155 species. Sixty-nine of the 70 species treated here are native to the Flora region. The other species, M. diversiglumis, is included because it was recently reported from Texas, but no specimens supporting the report have been found. It may be based on a misidentification. Within the Flora region, Muhlenbergia is represented best in the southwestern United States. Muhlenbergia montana is an important range grass in the southwestern United States and northern Mexico.

In the key and descriptions, puberulent refers to having hairs so small that they can only be seen with a 10 hand lens.


SELECTED REFERENCES Douglas, G.W., D. Meldinger, and J. Pojar. 2002. Illustrated Flora of British Columbia, vol. 8. British Columbia Ministry of Sustainable Resource Management and British Columbia Ministry of Forests, Victoria, British Columbia, Canada. 457 pp.; Gustafson, D.J. and P.M. Peterson. 2007. Re-examination of Muhlenbergia capillaris, M. expansa, and M. sericea (Poaceae: Muhlenbergiinae). Journal of the Botanical Research institute of Texas 1: 85-89; Herrera-Arrieta, Y. 1998. A revision of the Muhlenbergia montana (Nutt.) Hitchc. complex (Poaceae: Chloridoideae). Brittonia 50:23-50; Hitchcock, A.S. 1935b. Muhlenbergia Schreb. Pp. 431-476 in M.A. Howe, H.A. Gleason, and J.H. Barnhart (eds.). North American Flora, vol. 17, part 6. New York Botanical Garden, New York, New York, U.S.A. 64 pp.; Hitchcock, A.S.1951 [title page 1950]. 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.; Kartesz, J. and C.A. Meacham. 1999. Synthesis of the North American Flora, Version 1.0 (CD-ROM). North Carolina Botanical Garden, Chapel Hill, North Carolina, U.S.A.; Kearney, T.H. and R.H. Peebles. 1951. Arizona Flora. University of California Press, Berkeley and Los Angeles, California, U.S.A. 1032 pp.; McGregor, R.L., T.M. Barkley, R.E. Brooks, and E.K. Schofield. 1986. Flora of the Great Plains. Contribution No. 84-135-B, Division of Biology, Kansas Agricultural Experiment Station, Kansas State University. Contribution No. 1254, Department of Botany, North Dakota Agricultural Experiment Station, North Dakota State University. University Press of Kansas, Lawrence, Kansas, U.S.A. 1392 pp.; Morden, C.W. and S.L. Hatch. 1984. Cleistogamy in Muhlenbergia cuspidata (Poaceae). Sida 10:254-255; Morden, C.W. and S.L. Hatch. 1996. Morphological variation and synopsis of the Muhlenbergia repens complex (Poaceae). Sida 17:349-365; Peterson, P.M. 2000. Systematics of the Muhlenbergiinae (Chloridoideae: Eragrostideae). Pp. 195-212 in S.W.L. Jacobs and J. Everett (eds.). Grasses: Systematics and Evolution. International Symposium on Grass Systematics and Evolution (3rd:1998). CSIRO Publishing, Collingwood, Victoria, Australia. 408 pp.; Peterson, P.M. and C.R. Annable.1991. Systematics of the annual species of Muhlenbergia (Poaceae-Eragrostideae). Syst. Bot. Monogr. 31:1-109; Peterson, P.M. and Y. Herrera-Arrieta. 2001. A leaf blade anatomical survey of Muhlenbergia (Poaceae: Muhlenbergiinae). Sida 19:469-506; Soderstrom, T.R. 1967. Taxonomic study of subgenus Podosemum and section Epicampes of Muhlenbergia (Gramineae). Contr. U.S. Natl. Herb. 34:75-189; Swallen, J.R.1932. Five new grasses from Texas. Amer. J. Bot. 19:436-442; Welsh, S.L., N.D. Atwood, S. Goodrich, and L.C. Higgins (eds.). 1993. A Utah Flora, ed. 2, revised. Monte L. Bean Life Science Museum, Brigham Young University, Provo, Utah, U.S.A. 986 pp.
1
Plants annual (2)
Plants perennial (20)
2
Lemmas unawned or mucronate, the mucros to 1 mm long (3)
Lemmas awned, the awns 1-32 mm long (9)
3
Glumes strigulose, at least on the margins or towards the apices, the hairs 0.1-0.3 mm long (4)
Glumes glabrous (6)
4
Pedicels of most spikelets strongly curved below the spikelets, often through 90° or more; anthers olivaceous, 0.6-1.2 mm long ..... 65. M. sinuosa
Pedicels of most spikelets straight to somewhat curved below the spikelets, rarely curved through 90°; anthers purplish, 0.2-0.7 mm long (5)
5
Sheaths and culm internodes strigulose; lemmas 1.3-2 mm long, the apices acute to acuminate, mucronate or shortly awned ..... 67. M. texana
Sheaths and culm internodes glabrous, sometimes scabridulous; lemmas 0.8-1.5 mm long, the apices obtuse to subacute, unawned ..... 66. M. minutissima
6
Panicles contracted, less than 0.5 cm wide; branches closely appressed at maturity; culms often rooting at the lower nodes ..... 38. M. filiformis
Panicles open or diffuse, 0.6-11 cm wide; branches spreading at maturity; culms not rooting at the lower nodes (7)
7
Primary panicle branches 0.5-3.2 cm long; pedicels stout, 1-3 mm long, 0.5-1.5 mm thick; lemmas mottled, with greenish-black and greenish-white areas ..... 70. M. ramulosa
Primary panicle branches 0.4-6.2 cm long; pedicels delicate, 0.2-10 mm long, about 0.02 mm thick; lemmas not mottled, purplish, plumbeous, or brownish (8)
8
Primary panicle branches diverging 80-100° from the rachises; branches not developing below the lower leaf nodes; ligules with lateral lobes (vertical extensions of the sheath margins); plants truly annual ..... 69. M. fragilis
Primary panicle branches diverging less than 80° from the rachises; branches developing below the lower leaf nodes; ligules without lateral lobes; plants perennial but often appearing annual ..... 42. M. uniflora
9
Upper glumes 2- or 3-veined, apices 2- or 3-toothed, not awned (10)
Upper glumes l-veined or veinless, entire, erose, or awned (11)
10
Lemma awns olive-green, sinuous to curled; lemmas widest near the middle, 1.7-2.2 mm long ..... 47. M. crispiseta
Lemma awns purplish, flexuous; lemmas widest near the base, 1.4-4.2 mm long ..... 48. M. peruviana
11
Lower glumes 2-veined, minutely to deeply bifid, the teeth aristate or with awns to 1.8 mm long; spikelets often in sessile-pedicellate pairs; disarticulation at the base of the pedicels (12)
Lower glumes, if present, veinless or l-veined, not bifid, unawned or with a single awn; spikelets borne singly; disarticulation above the glumes (13)
12
Glumes subequal to the lemmas; lemmas 2.5-4.5 mm long, those of the upper spikelets with awns 6-15 mm long ..... 63. M. depauperata
Glumes up to 2/3 as long as the lemmas; lemmas 3.5-6 mm long, those of the upper spikelets with awns 10-20 mm long ..... 64. M. brevis
13
Lemma awns 1-5 mm long (14)
Lemma awns 10-32 mm long (16)
14
Glumes 0.1-0.3 mm long, the lower glumes often almost absent; ligules 0.2-0.5 mm long ..... 13. M. schreberi
Glumes 0.8-1.8 mm long; lower glumes 0.8-1.6 mm long; ligules 0.9-2.5 mm long (15)
15
Pedicels 2-7 mm long, usually longer than the florets, usually divergent; lemmas 1.3-2 mm long; lemma awns 0.1-1(2) mm long; caryopses 0.8-1 mm long; paleas minutely appressed-pubescent on the lower 1/2, 1.3-2 mm long ..... 67. M. texana
Pedicels 1-2(3) mm long, usually shorter than the florets and appressed to the branches; lemmas (1.7)1.9-2.5 mm long; lemma awns 1.2-3.5 mm long; caryopses 1.3-2.3 mm long; paleas glabrous, 1.8-2.4 mm long ..... 68. M. eludens
16
Panicles secund; primary branches with 2-5 spikelets; secondary branches not developed; spikelets dimorphic with respect to the glumes, the glumes of the proximal spikelet on each branch subequal, to 0.7 mm long, orbicular and unawned, those of the distal spikelets evidently unequal, the lower glumes to 8 mm long and usually awned, the upper glumes orbicular, sometimes awned ..... 18. M. diversiglumis
Panicles not secund; primary branches always with more than 2 spikelets, usually with more than 5; secondary branches well-developed; spikelets monomorphic with respect to the glumes (17)
17
Ligules 0.3-0.9 mm long, membranous and ciliate; distal portion of the sheath margins with hairs to 1 mm long; lemmas subulate to lanceolate, with a scabrous line between the midvein and lateral veins, giving the lemmas a 5-veined appearance ..... 17. M. pectinata
Ligules 1-3(5) mm long, hyaline to membranous, often lacerate; sheath margins glabrous, even distally; lemmas lanceolate, smooth over most of their length, scabridulous to scabrous distally, not appearing 5-veined (18)
18
Cleistogamous panicles not present in the axils of the lower cauline leaves; upper glumes 1.5-2.8 mm long, acute ..... 14. M. tenuifolia
Cleistogamous panicles of 1-3 florets present in the axils of the lower cauline leaves; upper glumes 0.6-2 mm long, obtuse to subacute (19)
19
Lemmas 2.5-3.8(5.3) mm long; glumes 0.4-1.3 mm long; ligules 1-2 mm long ..... 15. M. microsperma
Lemmas 4-6.2(7.5) mm long; glumes 1-2 mm long; ligules 1.5-3 mm long ..... 16. M. appressa
20
Plants rhizomatous, usually not cespitose; rhizomes scaly and creeping (21)
Rhizomes absent; plants cespitose or bushy (50)
21
Panicles open, (2)4-20 cm wide; panicle branches capillary (0.05-0.1 mm thick), diverging 30-100° from the rachises at maturity (22)
Panicles contracted, 0.1-2(3) cm wide; panicle branches more than 0.1 mm thick, appressed or diverging up to 30(40)° from the rachises at maturity (26)
22
Lemmas awned, awns 1-12(20) mm long (23)
Lemmas unawned, sometimes mucronate with mucros to 0.3 mm long (24)
23
Blades stiff and pungent; lemma awns 1-1.5(2) mm long, straight; primary branches of the panicles appearing fascicled in immature plants ..... 32. M. pungens
Blades not stiff and pungent; lemma awns 4-12(20) mm long, flexuous; primary branches of the panicles not appearing fascicled ..... 24. M. arsenei
24
Culms compressed-keeled; blades conduplicate; panicles cylindrical, 4-8 cm wide ..... 39. M. torreyana
Culms terete to somewhat compressed-keeled near the base; blades usually flat, occasionally conduplicate; panicles ovoid, 4-16 cm wide (25)
25
Ligules 0.5-2 mm long, hyaline, with well-developed lateral lobes; blade margins and midveins prominent, white, thick ..... 41. M. arenacea
Ligules 0.2-1 mm long, ciliate, without lateral lobes; blade margins and midveins not prominent, greenish, not particularly thick ..... 40. M. asperifolia
26
Culms 100-300 cm tall, 3-6 mm thick, woody and bamboolike ..... 33. M. dumosa
Culms 4-100(140) cm tall, 0.5-2(3) mm thick, herbaceous, not bamboolike (27)
27
Blades 0.2-2(2.6) mm wide, flat, involute, or folded at maturity (28)
Blades (1.5)2-15 mm wide, flat at maturity (38)
28
Lemmas awned, the awns 1-25 mm long (29)
Lemmas unawned, mucronate, or shortly awned, the awns to l mm long (33)
29
Lemmas pubescent for 3/4 their length, the hairs about 1.5 mm long ..... 21. M. curtifolia
Lemmas scabridulous or pubescent for no more than 1/2 their length, the hairs often less than 1.5 mm long (30)
30
Lemma awns generally less than 4(6) mm long ..... 19. M. glauca
Lemma awns 4-25 mm long (31)
31
Lemmas and paleas mostly glabrous, the calluses with a few short hairs; ligules with lateral lobes, the lobes 1.5-3 mm longer than the central portion; culms erect; plants tightly cespitose at the base; sheaths and blades commonly with dark brown necrotic spots ..... 22. M. pauciflora
Lemma midveins and margins and paleas appressed-pubescent on the lower 1/3-2/3; ligules without lateral lobes or with lobes less than 1.5 mm longer than the central portion; culms decumbent; plants loosely cespitose at the base; sheaths and blades without necrotic spots (32)
32
Anthers orange, 1.5-2 mm long; lemmas elliptic, 2-3.5 mm long, the awns 10-20(25) mm long; panicles 0.3-1.8 cm wide ..... 23. M. polycaulis
Anthers purple, 1.3-3 mm long; lemmas lanceolate, 3.5-5 mm long, the awns 4-12(20) mm long; panicles 1-3(5) cm wide ..... 24. M. arsenei
33
Lemmas and paleas pubescent, the hairs 0.4-1.2 mm long (34)
Lemmas and paleas scabrous, glabrous, or with hairs less than 0.3 mm long (36)
34
Glumes acuminate, usually awned, the awns to 1.5 mm long; anthers orange; blades flat to involute distally, never arcuate ..... 19. M. glauca
Glumes acute, neither mucronate nor awned; anthers yellow, dark green, or purple; blades tightly involute, often arcuate (35)
35
Lemmas 2.6-4 mm long; glumes nearly as long as the lemmas; anthers 2.1-2.3 mm long ..... 20. M. thurberi
Lemmas 1.4-2.5 mm long; glumes 1/2-2/3 as long as the lemmas; anthers 0.9-1.4 mm long ..... 34. M. villiflora
36
Glumes more than 1/2 as long as the lemmas; lemmas 2.6-4.2 mm long, attenuate ..... 35. M. repens
Glumes 1/2 as long as the lemmas or less; lemmas 1.3-3.1 mm long; not attenuate (37)
37
Ligules 0.2-0.8 mm long; panicles usually partially included, the rachises usually visible between the branches ..... 36. M. utilis
Ligules 0.8-3 mm long; panicles exserted, the rachises usually hidden by the branches ..... 37. M. richardsonis
38
Glumes awn-tipped, 3-8 mm long (including the awns), about 1.3-2 times longer than the lemmas (39)
Glumes unawned or awn-tipped, 0.4-4 mm long (including the awns), from shorter than to about 1.2 times longer than the lemmas (40)
39
Internodes dull, puberulent, usually terete, rarely keeled; culms seldom branched above the base; ligules 0.2-0.6 mm long; anthers 0.8-1.5 mm long ..... 2. M. glomerata
Internodes smooth and polished for most of their length, elliptic in cross section and strongly keeled; culms much branched above the base; ligules 0.6-1.7 mm long; anthers 0.4-0.8 mm long ..... 1. M. racemosa
40
Lemmas usually completely glabrous, rarely with a few appressed hairs (41)
Lemmas with hairs, these sometimes restricted to the callus (42)
41
Culms 30-100 cm tall, bushy and much branched above; axillary panicles common, partly included or exserted from the sheaths; lemmas shiny, stramineous or purplish, not mottled; anthers 0.3-0.5 mm long ..... 5. M. glabrifloris
Culms 5-30 cm tall, often mat-forming; axillary panicles not present; lemmas dark greenish or plumbeous, sometimes mottled; anthers 0.9-1.6 mm long ..... 37. M. richardsonis
42
Lemma bases with hairs about as long as the florets, usually 2-3.5 mm long ..... 6. M. andina
Lemma bases glabrous or with hairs shorter than the florets, usually shorter than 1.5 mm (43)
43
Glumes unequal, the lower glumes 0.4-1.5 mm long, the upper glumes 0.8-1.9 mm long ..... 7. M. curtisetosa
Glumes subequal, 1-4 mm long (44)
44
Axillary panicles often present, always partly included in the sheaths; internodes smooth, shiny (45)
Axillary panicles, if present, exserted on elongated peduncles; internodes smooth, scabrous, or pubescent, sometimes smooth and shiny (46)
45
Ligules 0.2-0.6 mm long; leaves of the lateral branches often shorter and narrower than those of the main branches; glumes 1.4-2 mm long, 1/3-2/3 as long as the lemmas ..... 8. M. bushii
Ligules 0.7-1.7 mm long; leaves of the lateral branches similar in length and width to those of the main branches; glumes 2-4 mm long, about as long as the lemmas ..... 9. M. frondosa
46
Glumes much shorter than the lemmas, acute (47)
Glumes nearly as long as or longer than the lemmas, acuminate (48)
47
Anthers 0.4-1 mm long; lemmas unawned, or with a short awn less than 1 mm long; internodes and sheaths glabrous ..... 10. M. sobolifera
Anthers 1.1-2.2 mm long; lemmas awned (occasionally unawned), the awns to 12 mm long; internodes (and usually the base of the sheaths) pubescent ..... 11. M. tenuiflora
48
Anthers 1-1.7 mm long; sheaths scabrous; lemma awns 0.2-2.2 mm long; restricted to the Transverse Ranges of southern California ..... 4. M. californica
Anthers 0.3-0.8 mm long, sheaths smooth for most of their length; lemma awns to 18 mm long; widespread species, but not known from southern California (49)
49
Ligules 0.4-1 mm long; panicles dense; pedicels up to 2 mm long; anthers 0.3-0.5 mm long ..... 3. M. mexicana
Ligules 1-2.5 mm long; panicles not dense, pedicels 0.8-3.5 mm long; anthers 0.4-0.8 mm long ..... 12. M. sylvatica
50
Upper glumes usually 3-veined and 3-toothed; old sheaths flattened, ribbonlike or papery, sometimes spirally coiled (51)
Upper glumes usually 1-veined, (rarely 2- or 3-veined), rounded, obtuse, acute, or acuminate, entire or erose; old sheaths not flattened or papery, never spirally coiled (54)
51
Lemmas unawned, mucronate, or with awns to 5 mm long (52)
Lemmas awned, the awns (2)6-27 mm long (53)
52
Lower glumes awned, the awns to 1.6 mm long; blades 2-6 cm long, filiform, tightly involute, sharp-tipped ..... 43. M. filiculmis
Lower glumes unawned; blades (5)6-12 cm long, flat or loosely involute to subfiliform, not sharp-tipped ..... 44. M. jonesii
53
Upper glumes as long as or longer than the lemmas, the apices acuminate to acute, occasionally minutely 3-toothed; old sheaths conspicuously spirally coiled ..... 45. M. straminea
Upper glumes 1/3-2/3 as long as the lemmas, the apices truncate to acute, 3-toothed; old sheaths occasionally spirally coiled ..... 46. M. montana
54
Panicles loosely contracted, open, or diffuse, (1)2-40 cm wide; panicle branches usually not appressed at maturity, often naked basally (55)
Panicles narrow, 0.2-3(5) cm wide; branches appressed to ascending at maturity, usually spikelet-bearing their whole length (73)
55
Culms arising from the bases of old depressed culms; plants loosely matted, delicate; lemmas 1.2-2 mm long, unawned ..... 42. M. uniflora
Culms not arising from the bases of old depressed culms; plants cespitose, not delicate; lemmas 2-5 mm long, awned or unawned (56)
56
Lemmas unawned or with awns to 4(6) mm long (57)
Lemma awns 6-35 mm long (65)
57
Basal sheaths laterally compressed, usually keeled (58)
Basal sheaths rounded to somewhat flattened, not keeled (59)
58
Glumes longer than the lemmas; ligules 10-25 mm long, membranous throughout; lemmas 2-3 mm long, usually awned, the awns to 15 mm long, occasionally unawned ..... 49. M. emersleyi
Glumes shorter than the lemmas; ligules 3-12 mm long, firm and brown near the base, membranous distally; lemmas 3-4.2 mm long, awned, the awns 0.5-4 mm long ..... 50. M. involuta
59
Culms 10-60(70) cm tall, somewhat decumbent; blades 0.5-10(16) cm long (60)
Culms 40-160 cm tall, erect from the base; blades (8)10-100 cm long (62)
60
Blade margins and midveins conspicuous, thick, white, and cartilaginous; ligules 1-2 mm long ..... 29. M. arizonica
Blade margins not conspicuously thickened, greenish; ligules 2-9 mm long (61)
61
Blades arcuate, 0.3-0.9 mm wide, 1-3(5) cm long; usually no culm nodes exposed; most leaf blades reaching no more than 1/5 of the plant height ..... 30. M. torreyi
Blades not arcuate, 1-2.2 mm wide, 4-10(16) cm long; 1 or more culm nodes exposed; leaf blades reaching 1/4-1/2 of the plant height ..... 31. M. arenicola
62
Pedicels 0.1-2.5 mm long, usually shorter than the florets; glumes usually longer than the florets; ligules 10-30 mm long; panicle branches not capillary, appressed or spreading up to 60° from the rachises, the lower branches with 30-60 spikelets ..... 51. M. longiligula
Pedicels 3-50 mm long, longer than the florets; glumes usually shorter than the florets; ligules 1.8-10 mm long; panicle branches capillary, spreading 30-100° from the rachises, the lower branches with 5-20 spikelets (63)
63
Panicles about as long as wide, not diffuse, usually 10-20(30) cm long; branches and pedicels stiff or flexible ..... 55. M. reverchonii
Panicles longer than wide, diffuse, 15-60 cm long; branches and pedicels flexible (64)
64
Glumes more than 1/2 as long as the lemmas; lemmas usually unawned, if awned, the awns no more than 3 mm long ..... 52. M. expansa
Glumes less than 1/2 as long as the lemmas; lemmas usually awned, the awns to 18 mm long ..... 53. M. capillaris
65
Plants conspicuously branched, bushy in appearance; culms wiry, with geniculate, stiff, widely divergent branches ..... 26. M. porteri
Plants not conspicuously branched, not bushy in appearance, usually typical bunchgrasses; culms not wiry, when branched, the branches not both geniculate and widely divergent (66)
66
Basal sheaths laterally compressed, commonly keeled; glumes (excluding any awns) exceeding the florets; culms (50)80-150 cm tall ..... 49. M. emersleyi
Basal sheaths rounded; glumes (excluding any awns) exceeded by the florets; culms 30-160 cm tall (67)
67
Glumes apices puberulent or scabridulous, acuminate to acute; lemmas long-acuminate, the demarcation of the lemma body and awn not evident ..... 57. M. elongata
Glume apices glabrous or sparsely hirtellous, obtuse to acute, sometimes awned; lemmas acute to acuminate, the demarcation of the lemma body and awn evident (68)
68
Glumes neither awned nor mucronate; spikelets dark purple; lemmas scabrous distally (69)
Glumes usually awn-tipped or mucronate; spikelets stramineous, brown, or purplish; lemmas smooth or scabrous distally (70)
69
Panicles 8-41 cm wide, open, diffuse, the branches strongly divergent; pedicels 10-40(50) mm long; in the Flora region, restricted to the eastern United States, growing from Connecticut south to Kansas, Oklahoma, eastern Texas, and Florida ..... 53. M. capillaris
Panicles 2-5 (12) cm wide, loosely contracted to open, most branches appressed to ascending, occasionally a few diverging up to 80º ; pedicels 1-10 mm long; in the Flora region, restricted to the southwestern United States, growing from Arizona to western Texas ..... 56. M. rigida
70
Lemmas shiny, smooth; blades tightly involute, 0.2-1.2 mm wide; panicles 2-5 cm wide, loosely contracted; branches diverging up to 70º from the rachises ..... 58. M. setifolia
Lemmas not shiny, usually scabrous, at least distally; blades flat or involute, 1-4 mm wide; panicles 5-40 cm wide, loosely contracted to open; branches diverging 30º -100º from the rachises (71)
71
Panicles 10-20(30) cm long, about equally wide, not diffuse; branches spreading up to 80° from the rachises at maturity; spikelets stramineous, brownish or purple-tinged; lemmas awned, the awns 0.5-6 mm long ..... 55. M. reverchonii
Panicles 15-50(60) cm long, narrower than long, diffuse; branches spreading 30-100° from the rachises at maturity; spikelets usually purplish; lemmas unawned or, if awned, the awns to 35 mm long (72)
72
Upper glumes unawned or with awns to 5 mm long; lemmas without setaceous teeth or the teeth no more than 1 mm long; lemma awns 2-13(18) mm long ..... 53. M. capillaris
Upper glumes awned, the awns 2-25 mm long; lemmas with setaceous teeth 1-5 mm long; lemma awns 8-35 mm long ..... 54. M. sericea
73
Panicles spikelike, 0.1-1.2 cm wide, sometimes interrupted near the base; branches appressed, 0.3-1.2(4) cm long (74)
Panicles not spikelike, 0.6-5 cm wide; branches appressed, ascending, or diverging up to 70 , 0.2-13 cm long (78)
74
Culms 3-20(35) cm tall, often decumbent and rooting at the lower nodes; blades 1-4(6) cm long ..... 38. M. filiformis
Culms (15)20-150 cm tall, stiffly erect, not rooting at the lower nodes; blades 1.4-50 cm long, at least some more than 6 cm long (75)
75
Lemmas awned, awns 3-10 mm long; lemmas scabridulous, the veins and margins glabrous ..... 59. M. palmeri
Lemmas unawned, sometimes mucronate, the mucros up to 1 mm long; lemmas with hairs on the lower 1/6, the hairs sometimes extending to 3/4 of the lemma length over the midvein and margins (76)
76
Basal leaf sheaths rounded on the back; panicles 15-60 cm long ..... 62. M. rigens
Basal leaf sheaths compressed, the backs keeled; panicles 4-16 cm long (77)
77
Ligules 0.2-0.8 mm long; paleas glabrous; glume apices gradually acute to acuminate, mucronate, the mucros to 0.3 mm long ..... 27. M. cuspidata
Ligules 1-3(5) mm long; paleas pubescent between the veins; glumes abruptly narrowed, acute or obtuse, awned, the awns 0.5-1 mm long ..... 28. M. wrightii
78
Ligules 10-35 mm long, firm and brown basally, membranous distally; glumes as long as or longer than the floret (79)
Ligules 0.2-10 mm long, usually membranous throughout, sometimes firmer basally, never brownish; glumes shorter than the florets (80)
79
Basal sheaths rounded; lemmas unawned or with awns to 2 mm long; plants of Arizona and New Mexico ..... 51. M. longiligula
Basal sheaths compressed-keeled, at least basally; lemmas unawned or with awns to 4 mm long; endemic to south central Texas, sometimes grown as an ornamental ..... 60. M. lindheimeri
80
Lemma awns 0.5-6 mm long (81)
Lemma awns 6-40 mm long (85)
81
Blades 10-60 cm long (82)
Blades to 10 cm long (83)
82
Glumes acute, unawned; ligules 4-10 mm long, acute, lacerate; spikelets grayish-green ..... 61. M. dubia
Glumes acute to acuminate, awned, the awns to 1.5 mm long; ligules 1-3 mm long, truncate, ciliolate; spikelets yellowish-brown to purplish ..... 59. M. palmeri
83
Glumes 2-4 mm long; lemmas 3.5-5 mm long, the awns flexuous; ligules 1-2 mm long, with lateral lobes less than 1.5 mm longer than the central portion; anthers 1.3-3 mm long, purple ..... 24. M. arsenei
Glumes less than 2 mm long; lemmas 1.8-3(3.4) mm long, the awns straight; ligules 0.2-1.1 mm long, without lateral lobes; anthers 0.2-0.9 mm long, yellow (84)
84
Upper glumes veinless, 0.1-0.3 mm long; lower glumes rudimentary or lacking, veinless ..... 13. M. schreberi
Upper glumes 1(2)-veined, 0.8-1.9 mm long; lower glumes 0.4-1.5 mm long, veinless or 1-veined ..... 7. M. curtisetosa
85

Glumes 0.3-1 mm long, obtuse to acute, sometimes erose, not awned; anthers 0.9-1.6 mm long ..... 25. M. spiciformis

Glumes (1)1.2-3.5 mm long, acute to acuminate, usually awn-tipped; anthers 0.9-3 mm long (86)
86
Blades 15-50 cm long; lemma awns 3-10 mm long; plants of southern Arizona and Chihuahua, Mexico ..... 59. M. palmeri
Blades 1-15 cm long; lemma awns 4-30 mm long; plants of the southwestern United States, including southern Arizona (87)
87
Lemmas and paleas almost glabrous, with only a few short hairs on the calluses; ligules with lateral lobes, the lobes 1.5-3 mm longer than the central portion; culms erect and plants tightly cespitose at the base; sheaths and blades usually with dark brown necrotic spots ..... 22. M. pauciflora
Lemmas and paleas pubescent on the lower 1/3-2/3 of the midveins and margins; ligules without lateral lobes or with lobes less than 1.5 mm longer than the central portion; culms decumbent and plants loosely cespitose; sheaths and blades without necrotic spots (88)
88
Anthers 0.9-1.5 mm long, yellowish; panicles usually 7-20 cm long ..... 14. M. tenuifolia
Anthers 1.3-2 mm long, purplish or orange; panicles 2-13 cm long (89)
89
Anthers orange, 1.5-2 mm long; lemmas elliptic, 2-3.5 mm long, with awns 10-20(25) mm long; panicles 0.3-1.8 cm wide ..... 23. M. polycaulis
Anthers purple, 1.3-3 mm long; lemmas lanceolate, 3.5-5 mm long, with awns 4-12(20) mm long; panicles 1-5 cm wide ..... 24. M. arsenei


1.   Muhlenbergia racemosa (Michx.) Britton, Sterns & Poggenb.
Marsh Muhly

Plants perennial; rhizomatous, not cespitose. Culms 30-110 cm tall, 1-1.5 mm thick, stiffly erect, much branched above the middle, internodes mostly smooth, polished, glabrous or puberulent immediately below the nodes, elliptic in cross section and strongly keeled. Sheaths scabridulous, slightly keeled; ligules 0.6-1.5(1.7) mm, membranous, truncate, lacerate-ciliolate; blades 2-17 cm long, 2-5 mm wide, flat, usually scabrous or scabridulous, occasionally smooth. Panicles 0.8-16 cm long, 0.3-1.8 cm wide, lobed, dense; branches 0.2-2.5 cm, appressed; pedicels absent or to 1 mm, strigose. Spikelets 3-8 mm. Glumes subequal, 3-8 mm (including the awns), about 1.3-2 times longer than the lemmas, smooth or scabridulous distally, 1-veined, acuminate and awned, awns to 5 mm; lemmas 2.2-3.8 mm, lanceolate, pilose on the calluses, lower 1/2 of the midveins, and margins, hairs to 1.2 mm, apices scabridulous, acuminate, unawned or awned, awns to 1 mm; paleas 2.2-3.8(4.5) mm, lanceolate, intercostal region loosely pilose on the lower 1/2, apices acuminate; anthers 0.4-0.8 mm, yellowish. Caryopses (1.2)1.4-2.3 mm, fusiform, brown. 2n = 40.

Muhlenbergia racemosa grows on rocky slopes, beside irrigation ditches, in seasonally wet meadows, on the margins of cultivated fields, railways and roadsides, in prairies, on sandstone outcrops, on stream banks, and in forest ecotones at elevations of 30-3400 m. It is most common in the north central United States, but can be found at scattered locations throughout the western United States, and extends into northern Mexico.


2.   Muhlenbergia glomerata (Willd.) Trin.
Spike Muhly, Muhlenbergie Agglomérée

Plants perennial; rhizomatous, not cespitose. Culms 30-120 cm tall, 0.8-2.5 mm thick, erect, seldom branched above the base; internodes dull, mostly puberulent (sometimes sparsely so), terete, rarely keeled, strigose immediately below the nodes. Sheaths scabridulous, slightly keeled; ligules 0.2-0.6 mm, membranous, truncate, lacerate-ciliolate; blades 2-15 cm long, 2-6 mm wide, flat, usually scabrous or scabridulous, occasionally smooth. Panicles 1.5-12 cm long, 0.3-1.8 cm wide, lobed, dense; primary branches 0.2-2.5 cm, appressed; pedicels absent or to 1 mm, strigose. Spikelets 3-8 mm. Glumes subequal, 3-8 mm (including the awn), about 1.3-2 times longer than the lemmas, smooth or scabridulous distally, 1-veined, acuminate, awned, awns to 5 mm; lemmas 1.9-3.1 mm, lanceolate, pubescent on the calluses, midveins, and margins, hairs to 1.2 mm, apices scabridulous, acuminate, unawned or awned, awns to 1 mm; paleas 1.9-3.1 mm, lanceolate, loosely pilose between the veins, apices acuminate; anthers 0.8-1.5 mm, yellowish. Caryopses 1-1.6 mm, fusiform, brown. 2n = 20.

Muhlenbergia glomerata grows in meadows, marshes, bogs, alkaline fens, lake margins, stream banks, beside irrigation ditches and hot springs, and on gravelly slopes, in many different plant communities, at elevations of 30-2300 m. It is most common in southern Canada and the northeastern United States, but grows sporadically throughout the western United States. It is not known from Mexico.


3.   Muhlenbergia mexicana (L.) Trin.
Wirestem Muhly, Muhlenbergie Mexicaine

Plants perennial; rhizomatous, not cespitose. Culms 30-90 cm tall, 0.5-2 mm thick, erect, much branched above the base; internodes dull, puberulent or glabrous for most of their length, sometimes strigose immediately below the nodes. Sheaths smooth or scabridulous, somewhat keeled; ligules 0.4-1 mm, membranous, truncate, lacerate-ciliolate; blades 2-20 cm long, 2-6 mm wide, flat, scabrous or smooth, those of the secondary branches similar in length and width to those of the main branches. Panicles terminal and axillary, 2-21 cm long, 0.3-3 cm wide, dense; primary branches 0.3-5.5 cm, appressed or diverging up to 30° from rachises; pedicels to 2 mm, strigose; axillary panicles exserted on long peduncles. Spikelets 1.5-3.8 mm, often purple-tinged. Glumes subequal, 1.5-3.7 mm, equaling or slightly shorter than the lemmas, 1-veined, tapering from the bases to the acuminate apices, unawned or awned, awns to 2 mm; lemmas 1.5-3.8 mm, lanceolate, pubescent on the calluses, lower portion of the midveins, and margins, hairs shorter than 0.7 mm, apices scabridulous, acuminate, unawned or awned, awns to 10 mm; paleas 1.5-3.8 mm, narrowly lanceolate, apices acuminate; anthers 0.3-0.5 mm, yellow to purplish. Caryopses 1.1-1.6 mm, fusiform, brown. 2n = 40.

Muhlenbergia mexicana usually grows in mesic to wet areas such as moist prairies and woodlands, stream banks, roadsides, ditch banks, lake margins, swamps, bogs, and hot springs, at elevations 50-3300 m, and is found in many different plant communities. Despite its name, M. mexicana grows only in Canada and the United States.

Plants with awns 3-10 mm long belong to Muhlenbergia mexicana var. filiformis (Torr.) Scribn., and those without an awn or with awns less than 3 mm long to Muhlenbergia mexicana (L.) Trin. var. mexicana. Early in the flowering season, M. mexicana may be confused with plants of M. bushii in which the axillary panicles are poorly developed, but they differ in their dull internodes and the fact that the blades on the secondary branches are usually similar in length and width to those of the main branches.


4.   Muhlenbergia californica Vasey
California Muhly

Plants perennial; rhizomatous, not cespitose. Culms 30-70 cm tall, 0.7-1.5 mm thick, decumbent; internodes dull, smooth, and glabrous for most of their length, sometimes strigose immediately below the nodes. Sheaths shorter than the internodes, scabrous, margins whitish; ligules0.8-2 mm, membranous, truncate, ciliolate, irregularly toothed; blades 4-16 cm long, 2-6 mm wide, flat, scabridulous abaxially, scabrous to strigose adaxially. Panicles terminal, 5-13 cm long, 0.5-2.2 cm wide, dense; branches 0.5-3.2 cm, ascending, appressed or diverging up to 20° from the rachises; pedicels to 1.5 mm, stout, strigose; axillary panicles not present. Spikelets 2.8-4 mm. Glumes subequal, 2.5-4 mm, nearly as long as or slightly longer than the lemmas, scabrous (especially on the veins), 1-veined, tapering from the base to the acuminate apices, usually unawned, awns, if present, to 1.2 mm; lemmas 2.8-4 mm, narrowly lanceolate, with soft hairs on the calluses and lower portion of the lemma bodies, hairs to 1 mm, apices scabridulous, acuminate, awned, awns 0.2-2.2 mm; paleas 2.8-4 mm, subequal to the lemmas, narrowly lanceolate, with short (less than 1.5 mm), soft hairs on the lower 1/2, apices scabridulous, acuminate; anthers 1-1.7 mm, yellow. Caryopses 1.7-2 mm, fusiform, brown. 2n = 80.

Muhlenbergia californica grows in canyons, along moist ditches, and on sandy slopes, at elevations of 100-2150 m. It is endemic to the Transverse Ranges of southern California.


5.   Muhlenbergia glabrifloris Scribn.
Inland Muhly

Plants perennial; rhizomatous, not cespitose. Culms 30-100 cm tall, 0.5-2 mm thick, herbaceous, ascending or decumbent, bushy and much branched above; internodes smooth and shiny for most of their length, scabridulous or strigulose below the nodes. Sheaths glabrous, margins hyaline; ligules 0.5-1.5 mm, membranous, truncate, lacerate-ciliolate; blades 3-8 cm long, (1.5)2-4 mm wide, flat, glabrous. Panicles 2-6.5 cm long, 0.2-0.8 cm wide, lobed, dense; branches 0.3-2.5 cm, ascending, closely appressed; axillary panicles common, partly included in or exserted from the subtending sheaths; pedicels 0.3-2.2 mm, scabrous to strigulose. Spikelets 2.2-3.5 mm. Glumes subequal, 1.5-3.5 mm, from 3/4 as long as to longer than the lemmas, smooth or scabridulous near the apices, 1-veined; upper glumes acuminate, acute, unawned or awned, awns to 1.2 mm; lemmas 2.2-3.1 mm, narrowly lanceolate, shiny, stramineous or purplish, usually completely glabrous (rarely with a few appressed hairs), apices scabridulous, acuminate, unawned; paleas 2.2-3.1 mm, narrowly lanceolate; anthers 0.3-0.5 mm, yellow to purplish. Caryopses 1.2-1.4 mm, fusiform, brown. 2n = 40.

Muhlenbergia glabrifloris grows at the edge of dry forests, in prairies, thickets, and along roadsides in pine and oak associations, at elevations of 20-400 m. It is restricted to the southern portion of the central contiguous United States. It resembles M. frondosa, but differs from that species in its glabrous lemmas and shorter caryopses (1.2-1.4 mm rather than 1.6-1.9 mm).


6.   Muhlenbergia andina (Nutt.) Hitchc.
Foxtail Muhly

Plants perennial; rhizomatous, not cespitose. Culms 25-85 cm tall, 0.9-1.7 mm thick, ascending; internodes glabrous for most of their length, scabrous to strigose below the nodes. Sheaths scabridulous, especially basally; ligules 0.5-1.5 mm, membranous, truncate, lacerate to ciliate; blades 4-16 cm long, 2-4(5) mm wide, flat, scabrous abaxially, pubescent adaxially. Panicles 2-15 cm long, 0.5-2.8 cm wide, contracted, dense; primary branches 0.5-5 cm, appressed to strongly ascending; pedicels 0.5-1.5 mm, appressed, strigose. Spikelets 2-4 mm. Glumes equal to subequal, 2-4 mm, subequal to or longer than the florets, 1-veined, veins scabridulous, apices acuminate to awn-tipped; lemmas 2-3.5 mm, lanceolate, grayish-green, hairy on the calluses and lemma bases, hairs 2-3.5 mm, apices acuminate, awned, awns 1-10 mm; paleas 2-3.5 mm, lanceolate, bases with silky hairs between the veins, apices acuminate; anthers 0.4-1.5 mm, yellow. Caryopses 0.9-1.1 mm, cylindrical, yellowish-brown. 2n = 20.

Muhlenbergia andina grows in damp places such as stream banks, gravel bars, marshes, lake margins, damp meadows, around springs, and in canyons, at elevations of 700-3000 m. It grows only in the western part of southern Canada and the contiguous United States.


7.   Muhlenbergia curtisetosa (Scribn.) Bush

Plants perennial; occasionally rhizomatous. Culms 20-70 cm tall, less than 3 mm thick, erect, branched above; internodes smooth, shiny for most of their length, scabridulous or glabrous below the nodes. Sheaths glabrous, margins hyaline, old sheaths not flattened, papery, or spirally coiled; ligules 0.2-1.1 mm, membranous, truncate, sometimes ciliolate; blades 2-8.5 cm long, 2-5 mm wide, flat, smooth or scabridulous. Panicles 4.2-16.5 cm long, 0.2-1.5 cm wide, mostly exserted from the sheath; primary branches 0.8-7.2 cm, ascending to appressed; pedicels 0.6-3 mm, strigose. Spikelets 2.2-3.4 mm. Glumes shorter than the florets, veins scabridulous, unawned or awned, awns to 0.5 mm; lower glumes 0.4-1.5 mm, veinless (rarely 1-veined), usually truncate to rounded, occasionally acute, sometimes notched; upper glumes 0.8-1.9 mm, 1(2)-veined, acute to acuminate; lemmas 2.2-3(3.4) mm, lanceolate, hairy on the calluses and lower portion of the margins and midveins, hairs shorter than 1.5 mm, apices scabridulous, acuminate, awned, awns 0.5-4 mm, straight; paleas 2.2-3.1(3.4) mm, lanceolate, intercostal region shortly pilose on the lower 1/2, apices acuminate; anthers usually not developed, occasionally 1 or 2 present, 0.3-0.9 mm, yellow. Caryopses 1.4-1.6 mm, fusiform, brown. 2n = unknown.

Muhlenbergia curtisetosa grows in abandoned fields and forest openings, often near bogs, at elevations of 20-300 m. It may be a hybrid between M. schreberi (which contributes the short glumes) and either of two rhizomatous species, M. frondosa and M. tenuiflora.


8.   Muhlenbergia bushii R.W. Pohl
Nodding Muhly

Plants perennial; rhizomatous, not cespitose. Culms 30-100 cm tall, 1-2 mm thick, herbaceous; internodes smooth, shiny, usually glabrous throughout. Sheaths glabrous, usually smooth, occasionally scabridulous distally; ligules 0.2-0.6 mm, membranous, truncate, ciliolate; blades 5-15 cm long, 2-7 mm wide, flat, glabrous abaxially, glabrous, smooth or scabridulous adaxially, those of the lateral branches often shorter and narrower than those of the primary branches. Panicles terminal and axillary, 4-15 cm long, 0.1-0.7 cm wide, narrow, not dense; axillary panicles common, partly included in the sheaths; branches 0.5-4 cm, ascending to appressed; pedicels 1-4 mm, glabrous. Spikelets 2.6-3.3 mm, not imbricate along the branches. Glumes subequal, 1.4-2 mm, about 1/3-2/3 as long as the lemmas, smooth or scabridulous distally, 1(2)-veined, acuminate or acute, unawned or awned, awns to 1 mm; lemmas 2.6-3.3 mm, narrowly lanceolate, usually hairy on the calluses and lower 1/3 of the margins and midveins (rarely glabrous), hairs 0.5-1 mm, apices scabridulous, acuminate, unawned or awned, awns 0.5-7 mm; paleas 2.2-3.1 mm, shorter than the lemmas, narrowly lanceolate, intercostal region shortly pilose on the basal 1/3, apices acuminate; anthers 0.3-0.6 mm, yellow. Caryopses 1.5-1.8 mm, fusiform, brown. 2n = 40.

Muhlenbergia bushii grows in sandy alluvium, open thickets, dry woodlands,and flood plains, at elevations of 10-250 m in the central portion of the contiguous United States.

Early season plants, in which the axillary panicles are poorly developed, can be distinguished from those of M. mexicana by their shiny internodes and the tendency of the blades on the secondary branches to be shorter and narrower than those on the main branches.


9.   Muhlenbergia frondosa (Poir.) Fernald
Wirestem Muhly, Muhlenbergie Feuillée

Plants perennial; rhizomatous, not cespitose. Culms 50-110 cm tall, 0.7-1.8 mm thick, ascending, geniculate, or decumbent, bushy and much branched above; internodes smooth and shiny for most of their length, glabrous throughout. Sheaths glabrous, margins hyaline; ligules 0.7-1.7 mm, membranous, truncate, lacerate-ciliolate; blades 4-18 cm long, 2-7 mm wide, flat, glabrous, smooth or scabridulous, those of the lateral branches similar to those of the primary culms. Panicles 2-15 cm long, 0.3-2 cm wide, sometimes dense; axillary panicles common, partly included in the sheaths; primary branches 0.3-4.2 cm, ascending, appressed, occasionally diverging up to 30° from the rachises; pedicels 0.4-5 mm, smooth or scabrous. Spikelets 2.2-4 mm, imbricate along the branches. Glumes subequal, 2-4 mm, 3/4 as long as to longer than the lemmas, 1-veined, unawned or awned, awns to 2 mm; upper glumes acuminate to acute; lemmas 2.2-4 mm, narrowly lanceolate, hairy on the calluses, lower 1/3 of the midveins, and margins, hairs 0.3-0.8 mm, apices scabridulous, acuminate, unawned or awned, awns 0.1-13 mm; paleas 2.3-4 mm, narrowly lanceolate, acuminate; anthers 0.3-0.6 mm, usually yellow, occasionally purplish. Caryopses 1.6-1.9 mm, fusiform, brown. 2n = 40.

Muhlenbergia frondosa grows in forest borders, thickets, clearings, alluvial plains, and disturbed sites within deciduous forests, at elevations of 20-1000 m. It grows only in southern Canada and the contiguous United States. The Oregon specimen supposedly documenting the occurrence of this species in Oregon has been revised to M. mexicana, in part because it was puberulent below the nodes. It remains probable that it was introduced to Oregon with cranberry plants. [The map was generated from a database developed by the editors of FNA 25. Peterson did not have the opportunity to review the Oregon specimen of M. frondosa before publication].

Plants with unawned or shortly (less than 4 mm) awned lemmas can be called M. frondosa (Poir.) Fernald forma frondosa, and those with lemma awns 4-13 mm long, M. frondosa forma commutata (Scribn.) Fernald.


10.   Muhlenbergia sobolifera (Muhl.ex Willd.) Trin.
Rock Muhly

Plants perennial; rhizomatous, usually not cespitose. Culms 25-95 cm tall, 0.8-1.5 mm thick, erect or ascending; internodes smooth, shiny, and glabrous for most of their length, scabridulous immediately below the nodes. Sheaths glabrous, margins hyaline; ligules 0.3-1 mm, membranous, truncate, ciliolate; blades 4-16 cm long, 2-7 mm wide, flat, glabrous, usually smooth, occasionally scabridulous. Panicles 4-18 cm long, 0.2-0.8 cm wide, narrow, usually exserted; axillary panicles usually exserted, sometimes partially included in the subtending sheath; primary branches 0.6-4 cm, ascending to appressed; pedicels 0.3-1.6 mm, strigose. Spikelets 1.6-3 mm, erect, overlapping the next spikelet on the branch by 1/2 its length. Glumes equal to subequal, 1-2.5 mm, much shorter than the florets, scabridulous (particularly over the veins), 1-veined, narrowing from above the broad, overlapping bases to the acute apices, unawned or awned, awns to 1 mm; lemmas 1.6-2.8 mm, lanceolate, hairy on the calluses, lower 1/2 of the midveins, and margins, hairs 0.3-0.5 mm, apices acuminate, unawned or awned, awns to 1 mm; paleas 1.6-2.9 mm, lanceolate, basal 1/2 with hairs shorter than 1. 5 mm, apices scabridulous, acuminate; anthers 0.4-1 mm, yellow. Caryopses 1-1.5 mm, fusiform, brown. 2n = 40.

Muhlenbergia sobolifera grows in dry upland forests, oak woodlands, and on rock outcrops of sandstone, chert, or limestone formations, at elevations of 0-1200 m. It is restricted to the Flora region.


11.   Muhlenbergia tenuiflora (Willd.) Britton, Sterns & Poggenb.
Slimflowered Muhly, Muhlenbergie Ténue

Plants perennial; rhizomatous, not cespitose. Culms 40-120 cm tall, less than 2 mm thick, erect; internodes mostly pubescent, retrorsely hirsute to strigose below the nodes. Sheaths mostly glabrous, usually pubescent near the base, scabridulous distally; ligules 0.4-1.2 mm, membranous, truncate, ciliolate; blades 6-20 cm long, 4-10(15) mm wide, flat, glabrous and smooth abaxially, occasionally scabridulous adaxially. Panicles usually terminal, 10-33 cm long, 0.2-0.8 cm wide, exserted; branches 1-10 cm, ascending to appressed; pedicels 1-6 mm, strigose. Spikelets 2.6-4.5 mm, overlapping the next spikelet on the branch by 1/4 of its length. Glumes subequal, 1.3-3 mm, shorter than the lemmas, 1-veined (lower glumes rarely 2- or 3-veined), tapering from near the base, bases overlapping, apices scabridulous, acute, unawned or awned, awns to 1 mm; lemmas 2.6-4.5 mm, lanceolate to narrowly lanceolate, usually pubescent on the calluses, lower 1/3 of the midveins, and margins (hairs sometimes restricted to the callus), hairs shorter than 1.2 mm, apices acute or acuminate, usually awned, awns to 12 mm; paleas 2.6-4.5 mm, lanceolate to narrowly lanceolate, shortly pilose on the lower portion, apices acuminate; anthers 1.1-2.2 mm, yellowish. Caryopses 2-2.3 mm, fusiform, brown. 2n = 40.

Muhlenbergia tenuiflora grows only in the Flora region, usually being found on sandy or rocky slopes derived from sandstone, chert, or limestone formations, in mixed hardwood and oak-hickory forests, at elevations of 40-1500 m. It resembles the Asiatic species M. curviaristata (Ohwi) Ohwi.


12.   Muhlenbergia sylvatica (Torr.) Torr. ex A. Gray
Woodland Muhly, Muhlenbergie des Bois

Plants perennial; rhizomatous. Culms 40-110 cm tall, 1-2 mm thick, erect; internodes puberulent for most of their length, strigose below the nodes. Sheaths glabrous and smooth for most of their length, scabridulous distally, margins hyaline; ligules 1-2.5 mm, membranous, truncate, lacerate-ciliolate; blades 5-18 cm long, 3-7 mm wide, flat, scabrous to scabridulous, occasionally smooth. Panicles terminal and axillary, 6-21 cm long, 0.2-1 cm wide, narrow, not dense; axillary panicles usually exserted at maturity; branches 0.8-6 cm, ascending to closely appressed; pedicels 0.8-3.5 mm, strigose. Spikelets 2.2-3.7 mm. Glumes subequal, 1.8-3 mm, nearly as long as the lemmas, 1-veined, tapering from near the base, apices scabridulous, acuminate, unawned or awned, awns to 1 mm; lemmas 2.2-3.7 mm, lanceolate to narrowly lanceolate, hairy on the calluses, lower 1/2 of the midveins, and margins, hairs 0.2-0.5 mm, apices scabridulous, acuminate, awned, awns 5-18 mm, purplish; paleas 2-3.5 mm, lanceolate, proximal 1/2 shortly pilose, apices scabridulous, acuminate; anthers 0.4-0.8 mm, yellow. Caryopses 1.4-2 mm, fusiform, brown. 2n = 40.

Muhlenbergia sylvatica grows in upland forests, along creeks and hollows, on rocky ledges derived from sandstone, shale, or calcareous parent materials, moist prairies, and swamps, at elevations from 30-1500 m. It is restricted to the Flora region, its primary range being southeastern Canada and the midwestern and eastern United States. Reports from British Columbia were based on a misidentification (Douglas et al. 2002). The record from Arizona is based on the report in Kearney and Peebles (1951) of a collection made by Toumey at Grapevine Creek in the Grand Canyon.


13.   Muhlenbergia schreberi J.F. Gmel.
Nimblewill

Plants perennial (appearing annual); usually cespitose, not rhizomatous, sometimes stoloniferous. Culms 10-45(70) cm, geniculate, often rooting at the lower nodes, glabrous or puberulent below the nodes; internodes often smooth, shiny, glabrous. Sheaths shorter than the internodes, glabrous for most of their length, margins shortly (0.3-1.2 mm) pubescent distally, not becoming spirally coiled when old; ligules 0.2-0.5 mm, truncate, erose, ciliate; blades (1)3-10 cm long, 1-4.5 mm wide, flat, smooth or scabridulous. Panicles 3-15 cm long, 1-1.6 cm wide, contracted, often interrupted below; branches 0.4-5.5 cm, appressed or diverging up to 30° from the rachises, spikelet-bearing to the base; pedicels 0.1-4 mm, scabrous to hirsute; disarticulation above the glumes. Spikelets 1.8-2.8 mm, borne singly. Glumes unequal, shorter than the florets, thin and membranous throughout, unawned; lower glumes lacking or rudimentary, veinless, rounded and often erose; upper glumes 0.1-0.3 mm, veinless; lemmas 1.8-2.8 mm, oblong-elliptic, mostly scabrous, calluses hairy, hairs to 0.8 mm, veins greenish, lower 1/4 of the midveins with a few appressed hairs, apices acute to acuminate, awned, awns 1.5-5 mm, straight; paleas 1.8-2.8 mm, oblong-elliptic, acute to acuminate; anthers 0.2-0.5 mm, yellow. Caryopses 1-1.4 mm, fusiform, brownish. 2n = 40, 42.

Muhlenbergia schreberi grows in moist to dry woods and prairies on rocky slopes, in ravines, and along sandy riverbanks, at elevations of 60-1600 m. It is also common in disturbed sites near cultivated fields, pastures, and roads at these elevations. Its geographic range includes central, but not northern, Mexico. Records from the western United States probably reflect recent introductions. The species is considered a noxious, invasive weed in California.


14.   Muhlenbergia tenuifolia (Kunth) Trin.
Slender Muhly

Plants annual or short-lived perennials; cespitose, not rhizomatous. Culms20-70 cm, erect or decumbent; internodes mostly scabridulous or smooth, always scabridulous below the nodes. Sheaths usually shorter than the internodes, glabrous, smooth or scabridulous, usually without necrotic spots, not becoming spirally coiled when old; ligules 1.2-3(5) mm, membranous throughout, acute, often lacerate; blades 2-13 cm long, 1.2-2.5 mm wide, flat or loosely involute, scabridulous or glabrous abaxially, scabrous adaxially, usually without necrotic spots. Panicles numerous, terminal and axillary, 7-20 cm long, 0.3-1.4(3) cm wide, contracted, often lax, nodding, interrupted below; primary branches 3.5-7.5 cm, ascending or diverging up to 70° from the rachises, spikelet-bearing to the base; pedicels 1-3 mm, antrorsely scabrous; disarticulation above the glumes. Spikelets 2-4 mm, often purplish, borne singly. Glumes 1.2-2.8 mm, shorter than the florets, 1-veined, veins scabrous, apices often erose, unawned or awned, awns to 0.5 mm; lower glumes 1.2-2 mm, acute to acuminate; upper glumes 1.5-2.8 mm, acute; lemmas 2-3.5(4) mm, lanceolate, mostly smooth, scabridulous distally, pubescent on the calluses, lower 1/2 of the midveins, and margins, hairs 0.5-1.5 mm, apices acuminate to acute, awned, awns 10-30 mm, scabrous, sinuous to flexuous; paleas 1.8-3.4(3.8) mm, lanceolate, sparsely villous basally, apices acuminate to acute; anthers 0.9-1.5 mm, yellowish. Caryopses 1-2.2 mm, narrowly fusiform, brownish. Cleistogamous panicles not present. 2n = 20, 40.

Muhlenbergia tenuifolia grows in grama grasslands and pine-oak woodlands on rocky slopes, limestone rock outcrops, gravelly roadsides, and in sandy drainages, at elevations of 1200-2200 m. Its range extends through Mexico to northern South America.


15.   Muhlenbergia microsperma (DC.) Trin.
Littleseed Muhly

Plants annual, sometimes appearing as short-lived perennials; tufted. Culms10-80 cm, often geniculate at the base, much branched near the base; internodes mostly scabridulous or smooth, always scabridulous below the nodes. Sheaths often shorter than the internodes, glabrous, smooth or scabridulous; ligules 1-2 mm, membranous to hyaline, truncate to obtuse; blades 3-8.5(10) cm long, 1-2.5 mm wide, flat or loosely involute, scabrous abaxially, strigulose adaxially. Panicles 6.5-13.5 cm long, 1-6.5 cm wide, not dense, often purplish; branches 1.6-4 cm, ascending or diverging up to 80° from the rachises, spikelet-bearing to the base; pedicels 2-6 mm, appressed to divaricate, antrorsely scabrous; disarticulation above the glumes. Spikelets 2.5-5.5 mm, borne singly. Glumes 0.4-1.3 mm, exceeded by the florets, 1-veined, obtuse, often minutely erose; lower glumes 0.4-1 mm; upper glumes 0.6-1.3 mm; lemmas 2.5-3.8(5.3) mm, narrowly lanceolate, mostly smooth, scabridulous distally, hairy on the calluses, lower 1/2 of the margins, and midveins, hairs 0.2-0.5 mm, apices acuminate, awned, awns 10-30 mm, straight to flexuous; paleas 2.2-4.8 mm, narrowly lanceolate, acuminate; anthers 0.3-1.2 mm, purplish. Caryopses 1.7-2.5 mm, fusiform, reddish-brown. Cleistogamous panicles with 1-3 spikelets present in the axils of the lower leaves. 2n = 20, 40, 60.

Muhlenbergia microsperma grows on sandy slopes, drainages, cliffs, rock outcrops, and disturbed roadsides, at elevations of 0-2400 m. It is usually found in creosote scrub, thorn-scrub forest, sarcocaulescent desert, and oak-pinyon woodland associations. Its range extends from the southwestern United States through Central America to Peru and Venezuela. Morphological variation among and within its populations is marked.


16.   Muhlenbergia appressa C.O. Goodd.
Devil's-Canyon Muhly

Plants annual. Culms 10-42 cm, erect or decumbent, much branched below; internodes mostly scabrous, scabrous or hispidulous below the nodes. Sheaths usually shorter than the internodes, flattened below, glabrous, scabridulous or smooth, striate; ligules 1.5-3 mm, hyaline, acute, lacerate, with lateral lobes; blades 1-5(7) cm long, 0.8-1.6(2) mm wide, flat or involute, scabrous abaxially, pubescent adaxially. Panicles 4-23 cm long, 0.5-2 cm wide, usually partially included in the subtending sheaths at maturity; primary branches 20-45 mm, ascending, closely appressed; pedicels 1-5 mm, appressed, scabrous; disarticulation above the glumes. Spikelets 4-7.5 mm, borne singly. Glumes 1-2 mm, 1-veined, veins conspicuous, scabrous, and greenish basally, apices obtuse to subacute, often erose; lemmas 4-6.2(7.5) mm, narrowly lanceolate, terete, mostly smooth,scabrous distally, hairy on the calluses and lower 1/4 of the margins, hairs 0.2-0.3 mm, whitish, lemma bodies not appearing 5-veined, apices acuminate, awned, awns 10-30 mm, straight, scabrous; paleas 3.8-5.7(7) mm, narrowly lanceolate; anthers 0.3-1.1 mm, purplish. Caryopses 1.6-3 mm, narrowly fusiform, brownish to pinkish. Cleistogamous spikelets usually present in the axils of the lower leaves. 2n = unknown.

Muhlenbergia appressa grows in sandy drainages, canyon bottoms, rocky road cuts, and sandy slopes, at elevations of 20-1750 m. Its range extends from Arizona to Baja California, Mexico. It grows in grama grasslands, oak-juniper woodlands, and chaparral associations.


17.   Muhlenbergia pectinata C.O. Goodd.
Combtop Muhly

Plants annual. Culms 10-33 cm, erect or decumbent, sometimes rooting at the lower nodes; internodes glabrous. Sheaths usually longer than the internodes, glabrous, margins sparsely hairy distally, hairs to 1 mm, coarse; ligules 0.3-0.9 mm, membranous, truncate, ciliate; blades 1-6 cm long, 0.6-2 mm wide, flat to loosely involute, appressed-pubescent to sparsely pilose. Panicles 4-12 cm long, 0.5-2.6(4) cm wide; primary branches 2-3.5 cm, appressed or diverging up to 70° from the rachises; pedicels 1-3 mm, glabrous, appressed; disarticulation above the glumes. Spikelets 2.5-5 mm, borne singly. Glumes glabrous, 1-veined, acute to acuminate, unawned or awned, awns to 1.5 mm; lower glumes 0.8-1.7 mm, entire; upper glumes 1-2(3) mm; lemmas (2.5)3-4.5(5) mm, subulate to lanceolate, calluses appressed-pubescent, lemma bodies appearing 5-veined (the intermediate "veins" are actually rows of short barbs on top of folded epidermal ridges), lateral veins occasionally ciliate, apices acuminate, awned, awns 10-32 mm, slender, flexuous; paleas 2.4-4.4 mm, narrowly lanceolate, glabrous, acuminate; anthers 0.3-0.6 mm, yellowish. Caryopses 0.6-3.1 mm, narrowly fusiform, light brownish. 2n = 20.

Muhlenbergia pectinata grows on rock outcrops, rocky cliffs, canyon walls, steep slopes, and road cuts, at elevations of 45-2400 m in thorn-scrub forests, grama grasslands, and pine-oak woodlands. It is almost entirely restricted to vertical surfaces that are seasonally wet. Its range extends from southeastern Arizona to Oaxaca, Mexico.


18.   Muhlenbergia diversiglumis Trin.
Mixedglume Muhly

Plants annual; sprawling. Culms 16-50 cm, decumbent, rooting at the lower nodes; nodes retrorsely pilose; internodes smooth or scabridulous. Sheaths 1.5-8.5 cm, sparsely or densely pilose, hairs to 3 mm, papillose-based; ligules 0.5-0.8 mm, membranous, truncate, erose; blades 2-6 cm long, 1.5-4 mm wide, flat, bases distinctly narrowed to the junction with the sheath, surfaces scabridulous and sparsely pilose, hairs papillose-based. Panicles 6-10.5 cm long, 2.0-4.5 cm wide, secund, open; primary branches 0.8-3.5 cm, secund, spreading at right angles or somewhat reflexed, with 2-5 spikelets; secondary branches not developed; pedicels 1-5 mm, scabrous or shortly pilose, hairs papillose-based; disarticulation at the base of the primary branches. Spikelets 4-8 mm, dimorphic with respect to the glumes, proximal spikelets on each branch almost sessile. Glumes of proximal spikelets on each branch subequal, 0.2-0.7 mm, orbicular, truncate, often erose, unawned; glumes of distal spikelets on each branch markedly unequal; lower glumes to 8 mm, 1-veined, acute, usually awned, awns 0.5-3 mm; upper glumes orbicular, acute, sometimes awn-tipped; lemmas 4.0-7.6 mm, linear to broadly lanceolate, light greenish, smooth or scabrous, usually with greenish veins, apices acuminate, awned, awns 6-19 mm, usually straight, scabrous; paleas 3.7-6.8 mm, narrowly lanceolate, coarsely papillate or almost smooth, acuminate; anthers 0.4-0.8 mm, yellowish. Caryopses 1.8-3 mm, oblong-ovoid, flattened, brownish. 2n = 20.

Muhlenbergia diversiglumis has been collected from Galveston County, Texas. The species is native from Mexico to Peru and Venezuela, where it grows on moist cliffs, along water courses, sandy slopes, and road cuts, primarily in moist shaded environments of broadleaf evergreen forests and pine-oak forests, at elevations of 600-2500 m. The collection from Texas may represent a recent introduction.


19.   Muhlenbergia glauca (Nees) B.D. Jacks.
Desert Muhly

Plants perennial; rhizomatous, rhizomes slender, well-developed. Culms 25-60 cm tall, 1-2 mm thick, often decumbent, sometimes erect; internodes mostly scabrous, retrorsely hispidulous below the nodes. Sheaths longer than the internodes, scabridulous; ligules 0.5-2 mm, truncate to obtuse, erose or lacerate; blades 4-12 cm long, 1-2.6 mm wide, flat to involute distally, not arcuate, scabrous abaxially, hirsute or scabrous adaxially. Panicles 4-12(17) cm long, 0.3-2.4 cm wide, contracted, interrupted below; branches 0.3-3 cm, usually appressed, occasionally diverging up to 30° from the rachises; pedicels 0.1-1.2 mm, scabrous to hirsute. Spikelets 2.4-3.5 mm. Glumes equal, 1.5-3.5 mm, 1-veined, veins scabrous, apices acute or acuminate, usually awned, awns, if present, to 1.5 mm; lemmas 2.4-3.4 mm, elliptic, pubescent on the lower the 1/2 of the midveins and margins, hairs to 0.6 mm, tawny, apices acuminate to acute, awned, awns 0.1-3(5) mm; paleas 2.2-3.4 mm, elliptic, intercostal region pubescent on the lower 1/2, apices acuminate to acute; anthers 1.8-2.4 mm, orange. Caryopses 1.7-2 mm, fusiform, brownish. 2n = 60.

Muhlenbergia glauca grows on calcareous rocky slopes, cliffs, canyon walls, table rocks, and volcanic rock outcrops, at elevations of 1200-2780 m. Its range extends from the southwestern United States to central Mexico. M. glauca resembles M. polycaulis, but differs in its shorter lemma awns and strongly rhizomatous habit.


20.   Muhlenbergia thurberi (Scribn.) Rydb.
Thurber's Muhly

Plants perennial; rhizomatous, not cespitose. Culms 12-36 cm tall, 0.3-0.5 mm thick, often clumped, usually erect, somewhat decumbent at the base; internodes mostly or completely glabrous, sometimes strigose below the nodes. Sheaths shorter than the internodes, hirtellous near the margins; ligules 0.9-1.2 mm, membranous, truncate to obtuse, erose; blades 0.2-3.7 cm long, 0.2-1 mm wide, tightly involute, straight to arcuate, smooth or scabridulous abaxially, hirtellous adaxially. Panicles 0.7-5.5 cm long, 0.2-0.7 cm wide, contracted, not dense, sometimes interrupted below; primary branches 0.4-1.8 cm, appressed; pedicels 0.1-4 mm. Spikelets 2.6-4 mm. Glumes subequal, 1.6-3 mm, 1-veined, scabridulous on the veins, acute, unawned; lemmas 2.6-4 mm, lanceolate, hairy on the lower 3/4, hairs to 1.2 mm, tawny, apices acuminate, unawned or awned, awns to 1 mm; paleas 2.6-4 mm, lanceolate, intercostal region tawny pubescent; anthers 2.1-2.3 mm, yellowish-purple. Caryopses 2-2.2 mm, fusiform, light brownish. 2n = unknown.

Muhlenbergia thurberi usually grows in moist soil in seeps near canyon cliffs, sandstone slopes, and rocky ledges, at elevations of 1350-2300 m. The species appears to be restricted to the southwestern United States. It flowers from July to September.

Muhlenbergia thurberi resembles M. curtifolia, differing in its tightly involute blades, and longer anthers and ligules. The two species have been found growing within 50 m of each other in Apache County, Arizona, but in different habitats: M. curtifolia growing in a damp drainage areas whereas M. thurberi grew near a moist but dryer canyon cliff.


21.   Muhlenbergia curtifolia Scribn.
Utah Muhly

Plants perennial; rhizomatous, not cespitose. Culms 10-45 cm tall, 0.3-0.5 mm thick, erect or decumbent; internodes hirsute and strigose below the nodes. Sheaths shorter than the internodes, hirsute; ligules 0.2-0.6 mm, margins hyaline, apices truncate to obtuse, erose, ciliate; blades 0.5-4(5) cm long, 0.6-1.5(2.2) mm wide, awl-shaped, flat near the base, becoming slightly involute distally, strigose to scabrous abaxially, hirsute adaxially. Panicles 2-10 cm long, 0.2-1 cm wide, contracted, not dense; primary branches 0.3-2.5 cm, ascending to appressed; pedicels 0.1-3 mm. Spikelets 2.8-4 mm. Glumes equal, 2.5-4 mm, 1-veined, veins scabridulous, apices acute; lemmas 2.8-4 mm, lanceolate, hairy on the lower 3/4, hairs to 1.5 mm, tawny, midveins scabridulous distally, apices acuminate, awned, awns usually 1-6(12) mm, delicate, straight; paleas 2.8-4 mm, lanceolate, intercostal region tawny pubescent on the basal 3/4; anthers 1.2-1.6 mm, yellowish-purple. Caryopses 2-2.4 mm, fusiform, brownish. 2n = unknown.

Muhlenbergia curtifolia grows on damp ledges and in rock crevices of vertical cliffs, and beneath large calcareous boulders above the canyon floor, at elevations of 1600-2750 m, in the southwestern United States. It resembles M. thurberi, differing in its flatter leaf blades and shorter ligules and anthers. It also tends to grow in more mesic habitats than M. thurberi.


22.   Muhlenbergia pauciflora Buckley
New Mexican Muhly

Plants perennial; tightly cespitose, sometimes rhizomatous. Culms 30-70 cm tall, 0.7-1 mm thick, erect, geniculate and rooting at the lower nodes; internodes mostly glabrous, sometimes glaucous, often striate below the nodes. Sheaths usually shorter than the internodes, smooth or scabridulous, usually with dark brown necrotic spots, flat and spreading at maturity; ligules 1-2.5(5) mm, membranous, obtuse, with lateral lobes 1.5-3 mm longer than the central portion; blades (1)5-12(15) cm long, 0.5-1.5 mm wide, flat to involute, glabrous and smooth abaxially, scabridulous adaxially, often with dark brown necrotic spots. Panicles (2)5-15 cm long, 0.5-2.8 cm wide, contracted, interrupted below; primary branches 0.5-4(6) cm, appressed or diverging up to 30° from the rachises, spikelet-bearing to the base; pedicels 0.1-3 mm, scabrous. Spikelets3.5-5.5 mm, occasionally with 2 florets. Glumes equal, 1.5-3.5 mm, shorter than the lemmas, 1-veined, acuminate to acute, often erose, unawned or awned, awns to 2.2 mm; lemmas 3-5.5 mm, lanceolate, often purplish, mostly glabrous, calluses with a few short hairs, apices acuminate, scabridulous, awned, awns (5)7-25 mm, flexuous; paleas 3-5.5 mm, lanceolate, glabrous, acuminate; anthers 1.5-2.1 mm, yellowish or purplish. Caryopses 2-2.5 mm, fusiform, brownish. 2n = unknown.

Muhlenbergia pauciflora grows in open or closed forests on rocky slopes, cliffs, canyons, and rock outcrops of granitic or calcareous origin, at elevations of 1200-2500 m. Its range extends from the southwestern United States to central Mexico.


23.   Muhlenbergia polycaulis Scribn.
Cliff Muhly

Plants perennial; loosely cespitose, sometimes shortly rhizomatous. Culms 15-40(50) cm tall, 0.8-1.5 mm thick, erect or decumbent; internodes glabrous or strigulose for most of their length, including below the nodes. Sheaths usually shorter than the internodes, smooth or scabridulous, without necrotic spots, not becoming spirally coiled when old; ligules 0.5-2.5 mm, membranous, obtuse to acute, without lateral lobes; blades 3-10 mm long, 0.5-2 mm wide, flat or involute (occasionally folded), smooth or scabridulous abaxially, hirsute or scabridulous adaxially, without necrotic spots. Panicles 2-12 cm long, 0.3-1.8 cm wide, contracted, interrupted below; primary branches 0.5-4 cm, appressed or diverging up to 30° from the rachises, spikelet-bearing to the base; pedicels 0.1-1.5 mm, scabrous. Spikelets 2.5-4 mm, plump near the middle. Glumes subequal, (1)1.5-2.6 mm, exceeded by the florets, 1-veined, acute or acuminate, unawned or awned, awns to 1.4 mm; lemmas 2-3.5 mm, elliptic, widest near the middle, appressed-pubescent on the lower 1/2-2/3 of the midveins and margins, hairs to 0.5 mm, apices scabridulous, acuminate, awned, awns 10-20(25) mm, flexuous; paleas 2-3.5 mm, elliptic, intercostal region appressed-pubescent on the basal 1/2, apices acuminate; anthers1.5-2 mm, orange. Caryopses 1.5-2 mm, fusiform, brownish. 2n = 20, 40.

Muhlenbergia polycaulis grows in open vegetation on steep rocky slopes, canyon walls, cliffs, table rocks, and volcanic rock outcrops, at elevations of 1200-2400 m. Its range extends from the southwestern United States to central Mexico. It differs from M. glauca, with which it may be confused, in its longer lemma awns, shorter rhizomes, and loosely tufted habit.


24.   Muhlenbergia arsenei Hitchc.
Navajo Muhly

Plants perennial; rhizomatous, rhizomes sometimes short and the plants loosely cespitose. Culms 10-50 cm tall, 0.4-1 mm thick, decumbent; internodes glabrous or strigulose. Sheaths shorter than the internodes, strigulose or glabrous, usually without necrotic spots, not becoming spirally coiled when old; ligules 1-2 mm, membranous throughout, obtuse, strigulose or glabrous, erose or toothed, with lateral lobes, lobes less than 1.5 mm longer than the central portion; blades 1-6 cm long, 1-2 mm wide, flat to involute, smooth or scabridulous abaxially, hirsute adaxially, usually without necrotic spots. Panicles 4-13 cm long, 1-3(5) cm wide, not dense; primary branches 0.5-4 cm, appressed or diverging up to 30° from the rachises, spikelet-bearing to the base; pedicels 0.1-3 mm. Spikelets 3.5-5 mm. Glumes subequal, 2-4 mm, exceeded by the florets, 1-veined, scabrous on the veins and near the apices, apices acuminate, unawned or awned, awns to 1.2 mm; lemmas 3.5-5 mm, lanceolate, mostly purplish, veins conspicuously green, pubescent on the lower 1/3-1/2 of the midveins and margins, hairs to 1.5 mm, apices scabridulous, acuminate, awned, awns 4-12(20) mm, flexuous; paleas 3.5-5 mm, narrow-lanceolate, intercostal region pubescent, apices acuminate, veins sometimes extending into awns to 0.5 mm; anthers 1.3-3 mm, purple. Caryopses 2-2.3 mm, fusiform, brownish. 2n = unknown.

Muhlenbergia arsenei grows among granitic boulders, on rocky slopes, limestone rock outcrops, and in arroyos, at elevations of 1400-2850 m. Its range extends from the southwestern United States into Baja California, Mexico. It flowers from August to September.


25.   Muhlenbergia spiciformis Trin.
Longawn Muhly

Plants perennial; cespitose, not rhizomatous. Culms 25-80 cm, erect, wiry; internodes mostly glabrous, strigose or glabrous below the nodes. Sheaths scabridulous, not becoming spirally coiled when old; ligules 1-3 mm, membranous, acuminate, deeply lacerate; blades 2-12 cm long, 1-3 mm wide, flat to involute, scabridulous abaxially, hirtellous or scabrous adaxially. Panicles 4-18(20) cm long, 0.2-2.8 cm wide, contracted, not dense, sometimes interrupted below; panicle branches 0.6-5 cm, appressed or diverging up to 30° from the rachises, spikelet-bearing to the base; pedicels 0.1-3 mm. Spikelets 3-4 mm. Glumes unequal, 0.3-1 mm, shorter than the florets, 1-veined, unawned; lower glumes shorter than the upper glumes, obtuse to acute, sometimes erose; lemmas 2.8-4 mm, narrowly lanceolate, purplish, scabrous, sparsely appressed-pubescent on the calluses and lower 1/4 of the midveins and margins, hairs shorter than 0.3 mm, apices acuminate, awned, awns (10)20-40 mm; paleas 2.6-3.9 mm, narrowly lanceolate, intercostal region sparsely pubescent on the basal 1/3, apices acuminate, scabrous; anthers 0.9-1.6 mm, purplish. Caryopses 2-2.6 mm, fusiform, brownish. 2n = 40.

Muhlenbergia spiciformis grows on rocky slopes, cliffs, and calcareous rock outcrops, often in thorn-scrub and open woodland communities. Its elevational range is 450-2800 m; its geographic range extends from the southwestern United States to northern Mexico.


26.   Muhlenbergia porteri Scribn. ex Beal
Bush Muhly

Plants perennial; loosely cespitose from a knotty base, not rhizomatous, distinctly bushy in appearance. Culms 25-100 cm tall, 0.5-1.5 mm thick, erect, geniculate, wiry, freely branched, branches stiff, geniculate, widely divergent; internodes scabridulous throughout. Sheaths shorter than the internodes, glabrous; ligules 1-2.5(4) mm, truncate, lacerate, with lateral lobes; blades 2-8 cm long, 0.5-2 mm wide, flat or folded, smooth or scabridulous abaxially, scabridulous adaxially. Panicles 4-14 cm long, 6-15 cm wide, open, not dense, usually purple; primary branches 1-7.5 cm, diverging 30-90° from the rachises, stiff, naked basally; pedicels 2-13(20) mm, scabrous. Spikelets 3-4.5 mm. Glumes 2-3 mm, shorter than the lemmas, 1-veined, veins scabrous, apices gradually acute to acuminate, occasionally mucronate, mucros to 0.4 mm; lemmas 3-4.5 mm, lanceolate, purplish, appressed-pubescent on the lower 1/2-3/4 of the margins and midveins, apices acuminate, awned, awns 2-13 mm, straight; paleas 3-4.5 mm, lanceolate, acuminate; anthers 1.5-2.3 mm, purple to yellow. Caryopses 2-2.4 mm, oblong, compressed, yellowish-brown. 2n = 20, 23, 24, 40.

Muhlenbergia porteri grows among boulders on rocky slopes and on cliffs, and in dry arroyos, desert flats, and grasslands, frequently in the protection of shrubs, at elevations of 600-1700 m. Its geographic range extends from the southwestern United States to northern Mexico.

Muhlenbergia porteri is highly palatable to all classes of livestock, but is never abundant at any particular location.


27.   Muhlenbergia cuspidata (Torr. ex Hook.) Rydb.
Plains Muhly

Plants perennial; cespitose, with knotty bases, not rhizomatous. Culms 20-60 cm tall, 1-2 mm thick, erect, not rooting at the lower nodes; internodes mostly glabrous or sparsely hispidulous, always hispidulous below the nodes. Sheaths shorter than the internodes, laterally compressed, keeled, smooth or scabridulous, not becoming spirally coiled when old; ligules 0.2-0.8 mm, membranous, truncate; blades 2-22 cm long, 0.5-2.7(3.5) mm wide, flat to folded, smooth or scabridulous abaxially, strigose adaxially. Panicles 4-14 cm long, 0.1-0.8 cm wide, spikelike, not dense; primary branches 0.4-3 cm, appressed; pedicels 0.1-1.2(4) mm. Spikelets 2.5-3.6 mm, dark green or plumbeous, occasionally with 2 florets. Glumes subequal, 1.2-3 mm, about 3/4 as long as the spikelets, 1-veined, gradually acute to acuminate, occasionally mucronate, mucros to 0.3 mm; lemmas 2.5-3.6 mm, lanceolate, sometimes mottled with greenish-black areas, with short, appressed hairs on the basal 1/2-3/4 of the midveins and margins, apices acuminate, sometimes mucronate, mucros to 0.6 mm; paleas 2.4-3.6 mm, lanceolate, glabrous, acuminate; anthers 1.2-1.8 mm, greenish. Caryopses 1.6-2.3 mm, fusiform, brownish. 2n = 20.

Muhlenbergia cuspidata grows in dry, gravelly prairies, on gentle rocky slopes, rocky limestone outcrops, and in sandy drainages, at elevations of 300-1400 m, primarily in the central portion of the Flora region. It flowers from June to October.

Muhlenbergia cuspidata is often confused with M. richardsonis, but that species has rhizomes and longer ligules. Morden and Hatch (1984) found cleistogamous panicles in the lower sheaths of a plant from Benton County, Oklahoma.


28.   Muhlenbergia wrightii Vasey ex J.M. Coult.
Spike Muhly

Plants perennial; cespitose, not rhizomatous. Culms 15-60 cm tall, 1.5-2.5 mm thick, compressed, erect, not rooting at the lower nodes; internodes mostly hispidulous or glabrous, strigose to hispidulous below the nodes. Sheaths usually shorter than the internodes, smooth or scabridulous, compressed-keeled, not becoming spirally coiled when old; ligules 1-3(5) mm, membranous, truncate; blades 1.4-12 cm long, 1-3 mm wide, flat to folded, smooth or scabridulous abaxially, strigose adaxially. Panicles 5-16 cm long, 0.2-1.2 cm wide, spikelike, dense; primary branches 0.3-2 cm, appressed; pedicels 0.1-1.4 mm. Spikelets 2-3 mm, dark green or plumbeous. Glumes equal, 0.5-1.6 mm, usually 1/2-3/4 as long as the lemmas, 1-veined, scabridulous on the veins, acute or obtuse, abruptly narrowed to a short (0.5-1 mm) awn; lemmas 2-3 mm, lanceolate, appressed-pubescent on the basal 1/2-3/4 of the midveins and margins, hairs about 0.5 mm, apices scabridulous, acute to acuminate, mucronate, mucros 0.3-1 mm; paleas 1.9-3 mm, lanceolate, intercostal region pubescent, apices acute to acuminate; anthers 1.3-1.8 mm, greenish. Caryopses 1.2-2 mm, fusiform, brownish. 2n = unknown.

Muhlenbergia wrightii grows in gravelly prairies, on rocky slopes, and in meadows on granitic, sandstone, or limestone-derived soils, at elevations of 1100-3000 m. Its range extends from the southwestern United States to northern Mexico.


29.   Muhlenbergia arizonica Scribn.
Arizona Muhly

Plants perennial; cespitose, not rhizomatous. Culms 15-50 cm, erect to decumbent; internodes hispidulous or glabrous below the nodes. Sheaths from slightly shorter to slightly longer than the internodes, rounded to somewhat flattened but not keeled, hispidulous basally, glabrous distally, margins hyaline, not becoming spirally coiled when old; ligules 1-2 mm, hyaline, obtuse, minutely erose; blades 4-7 cm long, 0.8-2 mm wide, flat or folded, glabrous abaxially, scabridulous or hispidulous adaxially, midveins and margins conspicuous, thickened, white, and cartilaginous. Panicles 4-20 cm long, 4-15 cm wide, diffuse; primary branches 0.5-7.5 cm, capillary, diverging 40-90° from the rachises, naked basally; pedicels 2-16 mm, flexuous. Spikelets 2.1-3.1 mm. Glumes equal, 1-1.5 mm, 1-veined, apices scabridulous, obtuse to acute, sometimes minutely erose, unawned; lemmas 2-3.1 mm, elliptic, purplish, appressed-pubescent on the lower 3/4 of the midveins and margins, hairs to 0.6 mm, apices scabrous, acute, minutely bifid, awned, awns 0.5-1.1 mm; paleas 2.1-3.2 mm, elliptic, glabrous, acute; anthers 1.6-2.1 mm, purplish. Caryopses 1.3-1.7 mm, fusiform, sulcate dorsally, brownish. 2n = 20.

Muhlenbergia arizonica grows in sandy drainages and gravelly canyons, and on plateaus and rocky slopes in open desert grasslands, at elevations of 1220-2230 m. Its range extends from the southwestern United States into northwestern Mexico. Flowering is from August to October.


30.   Muhlenbergia torreyi (Kunth) Hitchc. ex Bush
Ring Muhly

Plants perennial; cespitose, not rhizomatous. Culms 10-40(50) cm, decumbent, usually all the nodes concealed by the sheaths; internodes mostly scabrous or smooth, hispidulous below the nodes. Leaves strongly basally concentrated, most blades not reaching more than 1/5 of the plant height; sheaths shorter than the internodes, rounded, not keeled, scabridulous or smooth, not becoming spirally coiled when old; ligules 2-5(7) mm, hyaline, acuminate, lacerate, often with lateral lobes; blades 1-3(5) cm long, 0.3-0.9 mm wide, tightly involute or folded, arcuate, scabridulous, midveins and margins not thickened, green, apices somewhat sharp-pointed. Panicles 7-21 cm long, 3-15 cm wide, diffuse; primary branches 1-8 cm, diverging 30-90° from the rachises, stiff, naked basally; pedicels 1-8 mm, sometimes appressed to the branches. Spikelets 2-3.5 mm. Glumes equal, 1.3-2.5 mm, scabridulous, 1-veined, apices acute to acuminate, minutely erose, unawned or awned, awns to 1.1 mm; lemmas 2-3.2(3.5) mm, narrowly elliptic to lanceolate, appressed-pubescent on the basal 1/2-3/4 of the margins and midveins, apices scabrous, acuminate, awned, awns 0.5-4 mm; paleas 2-3.2(3.5) mm, narrowly elliptic, intercostal region sparsely pubescent, apices acuminate; anthers 1.2-2.1 mm, greenish. Caryopses 1.7-2 mm, fusiform, brownish. 2n = 20, 21.

Muhlenbergia torreyi grows in desert grasslands and open woodlands on sandy mesas, calcareous rock outcrops, and rocky slopes, at elevations of 1000-2450 m. Its range extends from the southwestern United States to northern Mexico. It also grows, as a disjunct, in northwestern Argentina.


31.   Muhlenbergia arenicola Buckley
Sand Muhly

Plants perennial; cespitose, not rhizomatous. Culms (15)20-60(70) cm, somewhat decumbent, 1 or more nodes exposed; internodes hispidulous below the nodes. Leaves somewhat basally concentrated, most blades not reaching more than (1/4)1/2 of the plant height; sheaths usually a little shorter than the internodes, not keeled, scabridulous, margins hyaline, basal sheaths rounded, not becoming spirally coiled when old; ligules 2-9 mm, hyaline, acute, lacerate, often with lateral lobes; blades 4-10(16) cm long, 1-2.2 mm wide, not arcuate, flat, folded, or involute, scabrous, often glaucous, midveins and margins not thickened, green. Panicles 12-30 cm long, 5-20 cm wide, diffuse; primary branches 1-10 cm, diverging 30-80° from the rachises, naked basally; pedicels 1-4(6) mm. Spikelets 2.5-4.2 mm. Glumes equal, 1.4-2.5 mm, 1-veined, apices scabridulous, acute to acuminate, minutely erose, unawned or awned, awns to 1 mm; lemmas 2.5-4.2 mm, narrowly elliptic, usually purplish, scabrous distally, appressed-pubescent on the lower 1/2-3/4 of the margins and midveins, apices acuminate, awned, awns 0.5-4.2 mm; paleas 2.5-3.5 mm, narrowly elliptic, intercostal region sparsely pubescent, apices acuminate, with 2 short (0.1-0.2 mm) awns; anthers 1.5-2.1 mm, greenish. Caryopses 1.9-2.3 mm, fusiform, brownish. 2n = 80, 82.

Muhlenbergia arenicola grows on sandy mesas, limestone benches, and in valleys and open desert grasslands, at elevations of 600-2135 m. Its range extends from the southwestern United States to central Mexico. It also grows, as a disjunct, in northwestern Argentina.


32.   Muhlenbergia pungens Thurb. ex A. Gray
Sandhill Muhly

Plants perennial; rhizomatous, not cespitose. Culms 10-70 cm, decumbent below; internodes cinereous-lanate, glabrous, or scabrous for most of their length, always cinereous-lanate below the nodes. Sheaths longer than the internodes, cinereous-lanate below, glabrous and smooth or scabridulous distally; ligules 0.2-1 mm, densely ciliate, obtuse, with lateral lobes; blades 2-8 cm long, 1-2.2 mm wide, flat to tightly involute, scabrous abaxially, hirsute adaxially, stiff, pungent. Panicles (7)8-16(19) cm long, (2)4-14 cm wide, open; primary branches 1.5-8 cm, capillary, straight, lower branches diverging 70-90° from the rachises in mature plants, often appearing fascicled in immature plants; pedicels 10-25 mm. Spikelets 2.6-4.5 mm. Glumes equal, 1.2-3 mm, purplish near the base, smooth or scabridulous distally, 1-veined, acuminate or acute, unawned or awned, awns to 1 mm; lemmas 2.6-4.5 mm, lanceolate, purplish, scabridulous distally and on the margins, apices acuminate, awned, awns 1-1.5(2) mm, straight; paleas 2.6-4.5 mm, lanceolate, glabrous, acuminate, 2-awned, awns to 1 mm; anthers 1.8-2.6 mm, purplish. Caryopses 1.8-2.5 mm, fusiform, brownish. 2n = 26, 42, 60.

Muhlenbergia pungens grows in loose sandy soils near sand dunes to sandy clay loam slopes and flats in desert shrub and open woodlands, at elevations of 600-2500 m. It is known only from the western and central contiguous United States.


33.   Muhlenbergia dumosa Scribn. ex Vasey
Bamboo Muhly

Plants perennial; rhizomatous, loosely cespitose. Culms 100-300 cm tall, 3-6 mm thick, erect or ascending, woody below, branching at the middle and upper nodes, branches numerous, fascicled, and spreading; internodes glabrous for most of their length, puberulent or glaucous below the nodes. Sheaths glabrous, enlarged and flattened basally, somewhat chartaceous; ligules 0.2-0.6 mm, membranous, truncate; blades of the branch leaves 1.2-8(12) cm long, 0.7-2.2 mm wide, flat or involute, glabrous abaxially, hirtellous adaxially; blades of the cauline leaves, particularly the lower cauline leaves, absent or greatly reduced. Panicles numerous, terminal on the main culms and the branches, 1-4 cm long, 0.3-1.4 cm wide, lax, inconspicuous; primary panicle branches appressed or loosely spreading up to 40° from the rachises; pedicels 0.1-1.5 mm. Spikelets 2.2-3.1 mm, green or purplish. Glumes subequal, 1-1.7 mm, glabrous, 1-veined, acute to acuminate, occasionally mucronate, mucros to 0.5 mm; lemmas 2.3-3.1 mm, lanceolate, appressed-pubescent on the calluses and lower portion of the margins, apices acuminate, awned, awns 1-5 mm, flexuous; paleas 2.3-3.1 mm, narrowly lanceolate, appressed-pubescent basally, acuminate; anthers 1.5-2 mm, purplish. Caryopses 1.2-1.6 mm, fusiform, reddish-brown. 2n = 40.

Muhlenbergia dumosa grows on rocky slopes, canyon ledges, and cliffs, in areas protected from grazing animals in oak-pine and thorn-scrub forests and oak-grama savannahs, at elevations of 600-1800 m, from Arizona to southern Mexico.

The bladeless cauline leaves and abundant branching from the middle and upper nodes make 'Bamboo Muhly' a very apt English name. North American Indians used it, after boiling, for chest and bowel ailments. It is native from southern Arizona to southern Mexico, but is also grown as an ornamental in the southwestern United States.


34.   Muhlenbergia villiflora Hitchc.
Hairy Muhly

Plants perennial; rhizomatous, not cespitose. Culms 4-30 cm tall, to 2 mm thick, erect; internodes smooth or nodulose. Sheaths shorter than the internodes, smooth to nodulose; ligules 0.4-1.5 mm, membranous, acute, erose; blades 0.7-3 cm long, 0.2-1.2 mm wide, arcuate-spreading, tightly involute, glabrous abaxially, hirtellous adaxially. Panicles 1-5 cm long, 0.1-0.5 cm wide, contracted, not dense, usually completely exserted; branches 0.2-1.1 cm, appressed to ascending; pedicels 0.1-1.2 mm, setulose. Spikelets 1.4-2.5 mm. Glumes equal, 0.6-1.8 mm, 1/2-2/3 as long as the lemmas, glabrous, 1(2, 3)-veined, acute, unawned; lemmas 1.4-2.5 mm, lanceolate, green or purplish, midveins and margins densely villous for most of their length, hairs 0.4-1 mm, apices acute, unawned, sometimes mucronate, mucros to 0.5 mm; paleas 1.4-2.3 mm, lanceolate, intercostal region densely villous, apices acute; anthers 0.9-1.4 mm, yellow, dark green, or purple. Caryopses 1-1.4 mm, ellipsoid to fusiform, dark brown. 2n = 20, 40.

In the United States, Muhlenbergia villiflora grows in open ground with alkaline to calcareous soils and on gypsum rock flats, at elevations of 600-1200 m. It usually forms small, isolated populations.

Plants in the United States belong to Muhlenbergia villiflora var. villosa (Swallen) Morden. This variety differs from M. villiflora Hitchc. var. villiflora, which grows in Mexico, in its longer spikelets (1.8-2.5 mm versus 1.4-2.3 mm) and preference for alkaline to calcareous, rather than gypsiferous, soils.


35.   Muhlenbergia repens (J. Presl) Hitchc.
Creeping Muhly

Plants perennial; rhizomatous, not cespitose. Culms 5-42 cm tall, 0.5-1 mm thick, decumbent near the base, forming dense mats; internodes glabrous, slightly nodulose. Sheaths shorter or longer than the internodes, glabrous; ligules 0.1-1(1.8) mm, membranous, truncate, occasionally lacerate; blades 0.4-6 cm long, 0.5-1.4 mm wide, involute, glabrous, smooth or scabridulous adaxially. Panicles 1-9 cm long, 0.1-0.6 cm wide, contracted, not dense, usually partially included in the upper leaf sheaths; primary branches 0.2-3 cm, usually closely appressed at maturity, rarely diverging up to 40° from the rachises; pedicels 0.2-3.6 mm, setulose. Spikelets 2.6-4.2 mm, occasionally with 2 florets. Glumes subequal, 1.1-3.6 mm, from 1/2 as long as to equaling the lemmas, light green, 1(2-3)-veined, acute, unawned; lemmas 2.6-3.2(4.2) mm, lanceolate, dark greenish or mottled, glabrous or the calluses and margins appressed-pubescent, hairs to 0.3 mm, apices scabridulous, attenuate, usually mucronate, mucros 0.1-0.3 mm; paleas 2.1-3.3 mm, lanceolate, smooth or scabridulous, acute; anthers 0.7-1.4 mm, yellow to purplish. Caryopses 1.1-1.5 mm, ellipsoid to ovoid, brownish. 2n = 60, 70-72.

Muhlenbergia repens grows in open, sandy meadows, canyon bottoms, calcareous rocky flats, gypsum flats, and on rolling slopes and roadsides, at elevations of 100-3120 m. Its range extends from the southwestern United States to southern Mexico.


36.   Muhlenbergia utilis (Torr.) Hitchc.
Aparejograss

Plants perennial; rhizomatous, not cespitose. Culms 7-30 cm tall, 0.5-1 mm thick, erect to decumbent; internodes mostly smooth to slightly nodulose, minutely pubescent or glabrous below the nodes. Sheaths shorter or longer than the internodes, glabrous; ligules 0.2-0.8 mm, membranous, truncate; blades 0.5-4.7 cm long, 0.2-1.8 mm wide, usually involute, sometimes flat, often at right angles to the culm, glabrous abaxially, hirtellous adaxially. Panicles 1-5 cm long, 0.1-0.4 cm wide, contracted, usually partially included in the upper sheaths, rachises usually visible between the branches; primary branches 0.2-1.2 cm, usually closely appressed at maturity, rarely diverging up to 30° from the rachises; pedicels 0.1-1.1 mm, glabrous. Spikelets 1.4-2.4 mm. Glumes subequal, 0.5-1.4 mm, 1/3-1/2 as long as the lemmas, yellowish to light green, glabrous, 1(2-3)-veined, acute, unawned; lemmas 1.3-2.4 mm, lanceolate, green or purplish, glabrous or the calluses and margins appressed-pubescent, hairs shorter than 0.3 mm, apices acute, unawned; paleas 1-2 mm, lanceolate, glabrous, acute; anthers 0.7-1.4 mm, yellow to purplish. Caryopses 0.7-1.2 mm, ellipsoid to ovoid, brown. 2n = 20.

Muhlenbergia utilis grows in wet soils along streams, ponds, and depressions in grasslands and alkaline or gypsiferous plains, at elevations of 200-1800 m. Its range extends from the southern United States through Mexico to Costa Rica.


37.   Muhlenbergia richardsonis (Trin.) Rydb.
Mat Muhly, Muhlenbergie de Richardson

Plants perennial; rhizomatous, not cespitose, often mat-forming. Culms 5-30 cm tall, 0.4-1 mm thick, decumbent, geniculate, or erect; internodes usually nodulose (occasionally smooth) for most of their length, puberulent or nodulose below the nodes. Sheaths shorter or longer than the internodes, glabrous; ligules 0.8-3 mm, membranous, acute to truncate, erose; blades 0.4-6.5 cm long, 0.5-4.2 mm wide, flat or involute, straight or arcuate-spreading, glabrous abaxially, hirtellous adaxially. Panicles 1-15 cm long, 0.1-1.7 cm wide, exserted, narrow or spikelike, rachises usually concealed by the branches; primary branches 0.4-5 cm, usually closely appressed at maturity, rarely diverging up to 20° from the rachises; pedicels 0.2-2 mm, setulose. Spikelets 1.7-3.1 mm, occasionally with 2 florets. Glumes subequal, 0.6-2 mm, 1/3-1/2 as long as the lemmas, green, 1(2)-veined, acute, sometimes mucronate, mucros less than 0.2 mm; lemmas 1.7-2.6(3.1) mm, lanceolate, dark greenish, plumbeous, or mottled, glabrous, apices scabridulous, acute to acuminate, sometimes mucronate, mucros to 0.5 mm; paleas 1.2-2.4(2.9) mm, lanceolate, acute; anthers 0.9-1.6 mm, yellow to purplish. Caryopses 0.9-1.6 mm, narrowly ellipsoid, brown. 2n = 40.

Muhlenbergia richardsonis grows in open sites in alkaline meadows, prairies, sandy arroyo bottoms, talus slopes, rocky flats and the shores of rivers, at elevations of 60-3300 m. It is the most widespread species of Muhlenbergia in the Flora region, extending from the Yukon Territory to Quebec in the north and to northern Baja California, Mexico, in the south. Morden and Hatch (1996) reported that it also grows in Alaska, but no voucher specimen has been located.

Muhlenbergia richardsonis is often confused with M. cuspidata, which differs in lacking rhizomes and having shorter ligules, and sometimes with M. filiformis, which differs in being a weak annual with glabrous internodes and obtuse, erose glumes.


38.   Muhlenbergia filiformis (Thurb. ex S. Watson) Rydb.
Pull-Up Muhly

Plants annual (often appearing perennial), tufted. Culms (3)5-20(35) cm, erect or geniculate, often rooting at the lower nodes; internodes glabrous. Sheaths shorter or longer than the internodes, glabrous, smooth or scabridulous; ligules 1-3.5 mm, hyaline to membranous, rounded to acute; blades 1-4(6) cm long, 0.6-1.6 mm wide, flat or involute, smooth or scabridulous abaxially, scabrous or pubescent adaxially. Panicles 1.6-6 cm long, 0.2-0.5 cm wide, spikelike, interrupted near the base, long-exserted; primary branches 0.9-1.2 cm, closely appressed at maturity; pedicels 1-3 mm, scabrous. Spikelets 1.5-3.2 mm. Glumes greenish-gray, glabrous, 1-veined, rounded to subacute; lower glumes 0.6-1.4 mm; upper glumes 0.7-1.7 mm; lemmas (1.5)1.8-2.5(3.2) mm, lanceolate, dark greenish, appressed-pubescent on the margins and midveins, hairs shorter than 0.3 mm, apices scabridulous, acute to acuminate, unawned, sometimes mucronate, mucros shorter than 1 mm; paleas 1.6-2.6(3.1) mm, lanceolate, scabridulous distally; anthers 0.5-1.2 mm, purplish. Caryopses 0.9-1.5 mm, fusiform, reddish-brown. 2n = 18.

Muhlenbergia filiformis grows in open, moist meadows, on gravelly lake shores, along stream banks, and in moist humus near thermal springs, at elevations of 1060-3050 m. It is usually associated with yellow pine forests, but also grows in many other plant communities. Its range extends into northern Mexico.

Muhlenbergia filiformis resembles M. richardsonis, but differs in having glabrous internodes and subacute apices. Large, robust specimens have been referred to M. simplex Scribn. or M. filiformis var. fortis E.H. Kelso but, until there is more evidence to the contrary, it seems best to treat such plants as representing an extreme of the variation within M. filiformis.


39.   Muhlenbergia torreyana (Schult.) Hitchc.
New Jersey Muhly

Plants perennial; rhizomatous, not cespitose. Culms 30-75 cm, compressed and keeled; internodes mostly glabrous, strigose on the keels and below the nodes. Sheaths strigose on the keels, basal sheaths much shorter than those above; ligules 0.3-1 mm, firm, truncate, ciliate; blades 6-20 cm long, 1-3.5 mm wide, conduplicate, scabrous on both surfaces, tapering to a fine sharp point. Panicles 10-28 cm long, 4-8 cm wide, cylindrical, open; primary branches 3-10 cm long, 0.05-0.1 mm thick, capillary, diverging 30-40° from the rachises, never appearing fascicled; pedicels 1.5-9 mm, usually longer than the spikelets. Spikelets 1.1-2.2 mm, occasionally with 2 florets. Glumes equal, 1-2 mm, purplish, scabridulous, 1-veined, acute, unawned; lemmas 1.1-2.2 mm, lanceolate, plumbeous, scabridulous, apices acute, unawned; paleas 1-2.1 mm, lanceolate, scabridulous, acute; anthers 1-1.4 mm, orange-yellow, turning purple at maturity. Caryopses about 1 mm, fusiform, brownish. 2n = unknown.

Muhlenbergia torreyana grows in perennially wet or moist, usually seasonally inundated habitats such as the sphagnous margins of shallow ponds and seasonally wet depressions, often within pine-oak or oak barrens and at elevations of 0-150 m. Kartesz and Meacham (1999) report that it appears to have been eliminated from New York, Delaware, and Georgia but that, in addition to the locations shown on the map, it grows in Maryland and New Jersey. Hitchcock (1951) reported that it grew in Kentucky, but no specimens documenting its presence there have been located. It is rare even in those states where it is still growing.

Morphologically, Muhlenbergia torreyana resembles the western M. asperifolia but differs in its strigose, strongly compressed, keeled culms and less strongly divergent panicle branches.


40.   Muhlenbergia asperifolia (Nees & Meyen ex Trin.) Parodi
Scratchgrass

Plants perennial; rhizomatous, not cespitose, occasionally stoloniferous. Culms 10-60(100) cm, decumbent-ascending, bases somewhat compressed-keeled; internodes glabrous, shiny below the nodes. Sheaths glabrous, margins hyaline; ligules 0.2-1 mm, firm, truncate, ciliate, without lateral lobes; blades 2-7(11) cm long, 1-2.8(4) mm wide, flat, occasionally conduplicate, smooth or scabridulous abaxially, scabridulous adaxially, margins and midveins not conspicuously thickened, greenish, apices acute, not sharp. Panicles 6-21 cm long, 4-16 cm wide, broadly ovoid, open; primary branches 3-12 cm, capillary, lower branches spreading 30-90° from the rachises, never appearing fascicled; pedicels 3-14 mm, longer than the spikelets. Spikelets 1.2-2.1 mm, occasionally with 2 or 3 florets. Glumes equal, 0.6-1.7 mm, purplish, scabridulous, particularly on the veins, 1-veined, apices acute; lemmas 1.2-2.1 mm, lanceolate to oblong-elliptic, somewhat plumbeous, glabrous, usually smooth, occasionally scabridulous near the apices, apices acute, unawned or mucronate, mucros to 0.3 mm; paleas 1.2-2.1 mm, lanceolate, glabrous, acute; anthers 1-1.3 mm, greenish-yellow to purplish at maturity. Caryopses 0.8-1 mm, fusiform, brownish. 2n = 20, 22, 28.

Muhlenbergia asperifolia grows in moist, often alkaline meadows, playa margins, and sandy washes, on grassy slopes, and around seeps and hot springs, at elevations of 55-3000 m. Its geographic range includes northern Mexico. Muhlenbergia asperifolia is morphologically similar to the southeastern M. torreyana, but differs in having glabrous, weakly compressed culms and more widely divergent panicle branches.

The caryopses of Muhlenbergia asperifolia are frequently infected by a smut, Tilletia asperifolia Ellis & Everhart, which produces a globose body filled with blackish-brown spores.


41.   Muhlenbergia arenacea (Buckley) Hitchc.
Ear Muhly

Plants perennial; rhizomatous, not cespitose. Culms 10-30(40) cm, decumbent, terete to somewhat compressed-keeled near the base; internodes scabridulous below the nodes. Sheaths about 1/2 as long as the internodes, margins hyaline; ligules 0.5-2 mm, hyaline, with lateral, 1-2 mm lobes; blades 0.7-4(6) cm long, 0.5-1.7 mm wide, flat, occasionally folded, tapering, scabrous abaxially, strigulose adaxially, margins and midveins thickened, whitish, apices narrow, often sharp. Panicles 5-15 cm long, 4-14 cm wide, broadly ovoid, open; primary branches 2-8 cm, capillary, straight to slightly flexuous, diverging 45-80(100)° from the rachises, never appearing fascicled, naked proximally; pedicels 1-11 mm, usually longer than the spikelets. Spikelets 1.5-2.6 mm, occasionally with 2 florets. Glumes equal, 0.9-2 mm, 1-veined, usually acute to acuminate, occasionally erose and mucronate, mucros to 0.2 mm; lemmas 1.5-2.5 mm, lanceolate to oblong-elliptic, plumbeous to purplish, sparsely appressed-pubescent on the lower 1/2 of the margins and midveins, hairs to 0.3 mm, apices acute to obtuse, sometimes shallowly bilobed, mucronate, mucros to 0.3 mm; paleas 1.5-2.6 mm, lanceolate, glabrous, obtuse to acute; anthers 1-1.5 mm, yellowish to purplish. Caryopses 1-1.3 mm, elliptic, brownish. 2n = unknown.

Muhlenbergia arenacea grows in sandy flats, plains, alluvial fans, washes, depressions, and alkaline mesas in open grasslands, at elevations of 1000-2200 m. Its range extends from the southwestern United States into northern Mexico.


42.   Muhlenbergia uniflora (Muhl.) Fernald
Bog Muhly, Muhlenbergie Uniflore

Plants perennial; loosely matted. Culms 5-45 cm, arising from the bases of old depressed culms, compressed-keeled, developing branches below the lower leaf nodes; internodes mostly glabrous, sometimes minutely puberulent below the nodes. Sheaths longer than the internodes, keeled, keels scabridulous, not becoming papery or spirally coiled when old; ligules 0.5-1.5 mm, membranous, truncate to obtuse, erose, without lateral lobes; blades 1-15 cm long, 0.8-2 mm wide, flat to conduplicate, smooth or scabridulous abaxially, hirtellous adaxially, midveins thickened and whitish proximally. Panicles 2-20 cm long, (0.2)2.5-6 cm wide, diffuse; primary branches 0.4-6 cm long, about 0.1 mm thick, ascending, diverging 10-60° from the rachises, naked basally; pedicels 0.2-7 mm, glabrous. Spikelets 1.3-2.1 mm, dark purplish to plumbeous, occasionally with 2 florets. Glumes equal, 0.4-1.3 mm, glabrous, 1-veined, apices scabrous, acute to obtuse, sometimes erose or notched, unawned; lemmas 1.2-2 mm, oblong-elliptic, dark purplish to plumbeous, glabrous, faintly 3-veined, apices acute to obtuse, unawned; paleas 1.3-2.1 mm, oblong-elliptic, glabrous, acute to obtuse; anthers 0.6-0.9 mm, dark purple. Caryopses 0.6-0.8 mm, ovoid, brownish. 2n = 42.

Muhlenbergia uniflora grows in bogs, wet meadows, and lake shores in sandy or peaty, often acidic, soils, at elevations of 0-650 m. It is native to eastern North America, but was collected once in British Columbia, probably having been introduced from ship ballast, and was recently collected from a commercial cranberry bog in Oregon. The collection from Texas may also be an introduction.


43.   Muhlenbergia filiculmis Vasey
Slimstem Muhly

Plants perennial; cespitose, not rhizomatous. Culms 5-30(40) cm, erect, rounded near the base; internodes smooth or scabridulous. Sheaths longer than the lower internodes, glabrous, becoming flattened and papery or ribbonlike at maturity; ligules 2-4(5) mm, membranous, acute; blades 2-6 cm long, 0.4-1.6 mm wide, tightly involute, filiform, stiff, scabrous abaxially, sparsely hirtellous adaxially, apices sharp. Panicles 1.5-7 cm long, 0.4-2 cm wide, contracted, sometimes dense; primary branches 0.1-2.8 cm, mostly tightly appressed or diverging up to 30° from the rachises; pedicels 0.1-2 mm, scabrous. Spikelets 2.2-3.5 mm. Glumes subequal, 0.8-2.5 mm, scabridulous distally; lower glumes 1-veined, awned, awns to 1.6 mm; upper glumes usually 3-veined, apices truncate to acute, 3-toothed, teeth sometimes shortly awned, awns to 0.6 mm; lemmas 2.2-3.5 mm, lanceolate, yellowish mottled with dark green, sparsely appressed-pubescent on the lower portion of the midveins and margins, hairs to 0.4 mm, apices scabridulous, acute to acuminate, awned, awns 1-5 mm, straight or flexuous; paleas2.2-3.5 mm, lanceolate, acute to acuminate; anthers 1.5-2 mm, purplish. Caryopses 1.3-1.6 mm, fusiform, brownish. 2n = unknown.

Muhlenbergia filiculmis grows on rocky slopes, dry meadows, and dry gravelly flats in forest openings and grasslands, at elevations of 2500-3500 m in the southern Rocky Mountains and northern Arizona. Kartesz and Meacham (1999) report it as occurring in North Dakota and Utah, but neither of the sources cited (McGregor et al. 1986; Welsh et al. 1993) supports its occurrence in these states.

It is sometimes difficult to distinguish Muhlenbergia filiculmis from M. montana, but that species has longer spikelets and lemma awns, and leaf blades that are flatter and not sharply tipped.


44.   Muhlenbergia jonesii (Vasey) Hitchc.
Modoc Muhly

Plants perennial; tightly cespitose, not rhizomatous. Culms 18-50 cm, erect, rounded near the base; internodes glabrous. Sheaths glabrous, bases becoming flattened and papery, lower sheaths longer than the internodes; ligules 2-5 mm, membranous, acute to acuminate; blades (5)6-12 cm long, 1-2.5 mm wide, flat, becoming loosely involute to subfiliform, scabrous abaxially, hirsute adaxially, apices not sharp. Panicles 4-15 cm long, 1.5-4 cm wide, not dense; primary branches 0.5-5 cm, appressed or diverging up to 40° from the rachises; pedicels 0.5-6 mm, flattened, scabrous. Spikelets 2.8-3.5 mm. Glumes subequal, 0.6-1.8 mm, scabridulous distally, truncate to obtuse, unawned; lower glumes 1-veined; upper glumes 3-veined, 3-toothed, often erose; lemmas 2.8-3.5 mm, lanceolate, loosely pubescent on the basal 1/3 of the midveins and margins, hairs to 0.6 mm, apices scabridulous, acute, mucronate, mucros shorter than 1 mm; paleas 2.8-3.5 mm, lanceolate, acute; anthers 1.4-2.3 mm, purple. Caryopses 1.6-1.8 mm, fusiform, light brown. 2n = 20.

Muhlenbergia jonesii is endemic to northern California. It grows on open slopes, pumice flats, and in openings in pine forests, at elevations of 1130-2130 m.


45.   Muhlenbergia straminea Hitchc.
Screwleaf Muhly

Plants perennial; cespitose. Culms 25-70 cm, erect, rounded near the base; internodes glabrous. Sheaths glabrous, stiff, becoming flattened, ribbonlike or papery, and conspicuously spirally coiled when old; ligules (6)10-20 mm, hyaline, acuminate, lacerate; blades 7-25 cm long, 1-4 mm wide, flat to involute, scabrous abaxially, spiculate adaxially. Panicles 8-25 cm long, 0.5-3 cm wide, not dense; primary branches 0.6-8 cm, appressed or diverging up to 30° from the rachises; pedicels 0.2-5 mm, scabrous. Spikelets 3.5-7 mm, yellowish to pale greenish. Glumes (3)3.5-6(7) mm, scabridulous, unawned or awn-tipped; lower glumes shorter than the upper glumes, 1-veined; upper glumes equaling or exceeding the florets, 3-veined, acuminate to acute, occasionally 3-toothed, awned, awns to 1.5 mm; lemmas 3.5-5.5(6) mm, lanceolate, pubescent on the lower 1/2 of the midveins and margins, hairs to 1 mm, apices scabrous, acuminate, awned, awns 12-27 mm, flexuous; paleas 3.5-5.5 mm, lanceolate, pilose between the veins, apices scabridulous, acuminate; anthers 2-3.5 mm, purple. Caryopses 1.9-2 mm, fusiform, light brown. 2n = unknown.

Muhlenbergia straminea grows on rolling, rocky slopes, volcanic tuffs, canyon bottoms, and ridges, usually in open pine forests, at elevations of 1800-2600 m. It is known only from the southwestern United States.


46.   Muhlenbergia montana (Nutt.) Hitchc.
Mountain Muhly

Plants perennial; cespitose, not rhizomatous. Culms 10-80 cm, erect, rounded near the base; internodes glabrous. Sheaths smooth or scabridulous, becoming flattened, papery, and occasionally spirally coiled when old, lower sheaths longer than the internodes; ligules 4-14(20) mm, membranous, acute to acuminate; blades 6-25 cm long, 1-2.5 mm wide, flat, becoming involute, scabrous abaxially, hirsute adaxially. Panicles 4-25 cm long, (1)2-6 cm wide, not dense; primary branches 0.5-10 cm, appressed or diverging up to 40° from the rachises; pedicels 0.5-6.5 mm, scabrous. Spikelets 3-7 mm. Glumes subequal, (1)1.5-3.2(4) mm, smooth or scabridulous distally; lower glumes 1-veined, sometimes with a less than 1 mm awn; upper glumes 1/3-2/3 as long as the lemmas, 3-veined, truncate to acute, 3-toothed, teeth sometimes awned, awns to 1.6 mm; lemmas 3-4.5(7) mm, lanceolate, loosely to densely appressed-pubescent on the lower portion of the midveins and margins, hairs to 0.8 mm, apices acute to acuminate, awned, awns (2)6-25 mm, flexuous; paleas 3-4.5(7) mm, lanceolate, acute to acuminate; anthers 1.5-2.3 mm, purplish. Caryopses 1.8-2 mm, fusiform, light brown. 2n = 20, 40.

Muhlenbergia montana grows on rocky slopes and ridge tops and in dry meadows and open grasslands, at elevations of 1400-3500 m. Its range extends from the western United States to Guatemala. Muhlenbergia montana is sometimes difficult to distinguish from M. filiculmis, but that species has shorter spikelets and lemma awns and tightly involute or filiform, sharp blades.


47.   Muhlenbergia crispiseta Hitchc.
Mexicali Muhly

Plants annual; tufted. Culms 7-16 cm. Sheaths longer than the internodes, scabridulous or smooth, margins membranous; ligules 1.3-2 mm, membranous, rounded; blades 1-5 cm long, 0.7-1.4 mm wide, flat or involute, scabridulous or smooth abaxially, shortly pubescent adaxially. Panicles 1.8-4.5 cm long, 1.5-3 cm wide, long-exserted; primary branches 1.5-2.8 cm, ascending; pedicels 0.4-2 mm, often curved, scabrous. Spikelets 1.7-2.2 mm. Glumes whitish, mostly smooth, scabrous on the veins; lower glumes 1.2-1.6 mm, 1-veined, acute; upper glumes 1.6-1.8 mm, wider than the lower glumes, 2- or 3-veined, truncate, 2- or 3-toothed; lemmas 1.7-2.2 mm, lanceolate, widest near the middle, whitish with dark green patches, densely hairy on the calluses and lower portion of the lemma bodies, hairs to 0.5 mm, apices glabrous, acuminate, minutely bifid, awned, awns 8-18 mm, sinuous to crisped or curled, olive-green; paleas 1.1-1.7 mm, lanceolate, intercostal region loosely pilose on the proximal 2/3, apices acuminate; anthers 0.4-0.7 mm, purplish-red. Caryopses 0.5-1.1 mm, ellipsoid, brownish. 2n = 20.

Muhlenbergia crispiseta grows on rock outcrops, in rocky drainages, and on white tablelands, on soils derived from calcareous parent materials in pine-oak and pinyon-juniper woodlands, at elevations of 1900-2600 m. It is basically a Mexican species, with a disjunct population in Brewster County, Texas.


48.   Muhlenbergia peruviana (P. Beauv.) Steud.
Peruvian Muhly

Plants annual; tufted. Culms 3-27 cm, erect, glabrous. Sheaths usually longer than the internodes, smooth or scabridulous; ligules 1.5-3 mm, membranous, acute; blades 1-5 cm long, 0.6-1.5 mm wide, flat to involute, smooth or scabridulous abaxially, sometimes shortly pubescent adaxially. Panicles 2-8 cm long, 0.3-3.4 cm wide, contracted or open; primary branches 1-5 cm, diverging up to 80° from the rachises; pedicels 0.4-5 mm, smooth or scabrous. Spikelets 1.4-4.2 mm. Glumes smooth or scabridulous; lower glumes 0.8-2.8 mm, narrow to broadly lanceolate, 1-veined, acute, often awn-tipped; upper glumes 0.9-3 mm, wider than the lower glumes, lanceolate, (1)2-3-veined, truncate to acute, 2- or 3-toothed; lemmas 1.4-4.2 mm, widest near the base, purplish mottled with dark green, hairy on the calluses and lower 2/3 of the lemma bodies, hairs to 0.5 mm, apices acuminate, usually bifid and awned from between the teeth, teeth to 0.5 mm, awns 3-10 mm, flexuous, purplish; paleas 1.3-3.8 mm, narrowly lanceolate, acuminate to subacute; anthers 0.5-1 mm, purplish to yellowish. Caryopses 1-1.6 mm, fusiform, brownish. 2n = 30.

Muhlenbergia peruviana grows in open gravelly flats, meadows, rock outcrops, sandy washes, gravelly drainages, rocky slopes, disturbed road cuts, and volcanic flats, in yellow pine forest associations, at elevations of 2000-4600 m. Its primary distribution is to the south of the Flora region, extending from the southwestern United States through Mexico to Ecuador, Peru, Bolivia, and Argentina.

As treated here, Muhlenbergia peruviana includes what are sometimes identified as M. pulcherrima Scribn. ex Beal, M. pusilla Steud., and M. peruviana, sensu stricto. There are, however, numerous intermediates among the three extremes represented by these names.


49.   Muhlenbergia emersleyi Vasey
Bullgrass

Plants perennial; cespitose, not rhizomatous. Culms (50)80-150 cm, stout, erect, not conspicuously branched; internodes smooth for most of their length, smooth or scabridulous below the nodes. Sheaths shorter or longer than the internodes, glabrous or puberulent, basal sheaths laterally compressed, usually keeled; ligules 10-25 mm, membranous throughout, acuminate, lacerate; blades 20-50 cm long, 2-6 mm wide, flat or folded, scabrous abaxially, smooth or scabridulous adaxially. Panicles 20-45 cm long, 3-15 cm wide, loosely contracted to open, light purplish to light brownish; primary branches 1-17 cm, lax, loosely appressed or diverging up to 70° from the rachises, naked basally; pedicels 0.5-3 mm, smooth or scabridulous. Spikelets 2.2-3.2 mm. Glumes subequal, 2.2-3.2 mm, exceeding the florets, scabridulous to scabrous, faintly 1-veined, acute to obtuse, usually unawned, occasionally awned, awns to 0.2 mm; lemmas 2-3 mm, oblong-elliptic, shortly pubescent on the lower 1/2-3/4, apices acute, usually awned, sometimes unawned, awns to 15 mm, flexuous, purplish; paleas 1.8-2.9 mm, oblong-elliptic, acute; anthers 1.2-1.6 mm, yellowish to purplish. Caryopses 1.3-1.6 mm, fusiform, reddish-brown. 2n = 24, 26, 28, 40, 42, 46, 60, 64.

Muhlenbergia emersleyi grows on rocky slopes, gravelly washes, canyons, cliffs, and arroyos, often in soils derived from limestone, at elevations of 1200-2500 m, and is also grown as an ornamental. Its range extends from the southwestern United States through Mexico to Panama.

Muhlenbergia emersleyi differs from the closely related M. longiligula in its compressed-keeled sheaths, pubescent florets, and membranous ligules.


50.   Muhlenbergia involuta Swallen
Canyon Muhly

Plants perennial; cespitose, not rhizomatous. Culms 60-140 cm, erect; internodes puberulent or glabrous for most of their length, puberulent below the nodes. Sheaths shorter or longer than the internodes, smooth or scabridulous, tightly imbricate, yellowish-brown, basal sheaths laterally compressed, keeled, not becoming spirally coiled when old; ligules 3-12 mm, firm and brown basally, membranous distally, acute; blades 10-45 cm long, 1.6-5 mm wide, tightly folded, scabrous abaxially, hirsute adaxially. Panicles 18-40 cm long, 1.5-7 cm wide, loosely contracted to open, not dense; branches 1-10 cm, ascending or diverging up to 60° from the rachises, stiff, naked basally; pedicels 2-8 mm, hirtellous. Spikelets 3-4.2 mm, yellowish to purplish. Glumes subequal, 2-3 mm, exceeded by the florets, scabridulous or smooth, 1-veined, acute or obtuse, unawned; lemmas 3-4.2 mm, lanceolate, glabrous or appressed-pubescent on the lower 1/4 of the margins, apices acute to obtuse, usually bifid and awned, teeth to 0.3 mm, awns 0.5-4 mm, straight; paleas 3-4.2 mm, lanceolate, glabrous, acute to acuminate; anthers 1-1.8 mm, purplish. Caryopses not seen. 2n = 24.

Muhlenbergia involuta grows on rocky, calcareous slopes in openings and along canyons, at elevations of 150-500 m. It has only been found growing naturally in Texas, but it is also available commercially as an ornamental. Swallen (1932) suggested that M. reverchonii and M. lindheimeri were its parents; M. rigida seems to be another plausible possibility.


51.   Muhlenbergia longiligula Hitchc.
Longtongue Muhly

Plants perennial; cespitose, not rhizomatous. Culms 60-130 cm, stout, erect; internodes mostly smooth, sometimes scabridulous below the nodes. Sheaths shorter or longer than the internodes, smooth or scabridulous, not becoming spirally coiled, basal sheaths rounded; ligules 10-30 mm, firm and brown basally, membranous distally, acuminate to obtuse; blades (10)20-65 cm long, 3-6 mm wide, flat or inrolled at the margins, scabrous abaxially, scabridulous or smooth adaxially. Panicles 15-55 cm long, 1-15 cm wide, contracted to open, greenish-tan to purplish; primary branches 3-13 cm, narrowly ascending or diverging up to 60° from the rachises, stiff, spikelet-bearing to the base, lower branches with 30-60 spikelets; pedicels 0.1-2.5 mm, usually shorter than the spikelets, scabridulous or smooth, strongly divergent. Spikelets 2-3.5 mm. Glumes subequal, 2-3.5 mm, usually longer than the florets, scabridulous or smooth, 1(2)-veined, acute to acuminate, usually unawned, rarely awned, awns to 0.2 mm; lemmas 2-2.9 mm, oblong-elliptic, tan to purplish, smooth or scabridulous, apices acute, often bifid, teeth to 0.2 mm, unawned or awned, awns to 2 mm; paleas 2-3 mm, oblong-elliptic, scabridulous or smooth, acute; anthers 1-2.1 mm, yellowish to purplish. Caryopses 1.1-1.5 mm, fusiform, reddish-brown. 2n = 22, 24, 29, 30.

Muhlenbergia longiligula grows on rocky slopes, canyons, and rock outcrops derived from volcanic or calcareous parent materials, at elevations of 1220-2500 m. It is a common species in Arizona and southwestern New Mexico, and extends into northwestern Mexico. It may be confused with M. emersleyi, but differs from that species in its rounded basal leaf sheaths, glabrous lemmas, and panicle branches that are spikelet-bearing to the base. It is also similar to M. lindheimeri, but differs in its rounded basal sheaths.


52.   Muhlenbergia expansa (Poir.) Trin.
Savannah Hairgrass

Plants perennial; cespitose, not rhizomatous. Culms 60-100(150) cm, erect from the base, not conspicuously branched; internodes mostly glabrous, sometimes puberulent below the nodes. Sheaths glabrous or puberulent, rounded basally, becoming fibrous, not flat or spirally coiled, at maturity; ligules 1.8-5(10) mm, membranous, firm, strongly decurrent, obtuse; blades 20-50(80) cm long, 2-4 mm wide, flat or involute, smooth abaxially, scabrous adaxially. Panicles 15-50(60) cm long, 5-30 cm wide, longer than wide, diffuse; primary branches 2-20 cm, capillary, spreading 30-100° from the rachises, naked basally, lower branches with 5-20 spikelets; pedicels 4-50 mm, longer than the spikelets, capillary, flexible, widely divergent at maturity. Spikelets 3-5 mm, often purplish, sometimes brownish or bronze. Glumes subequal, 1.5-3.3 mm, shorter than the florets, glabrous; lower glumes 1-veined, unawned; upper glumes usually 1-veined, rarely 3-veined, acute to acuminate, often erose, sometimes mucronate; lemmas 3-5 mm, lanceolate, calluses shortly pubescent, apices acuminate, without setaceous teeth, usually unawned, if, as rarely, awned, awns 1-3 mm, clearly demarcated from the lemma bodies; paleas 2-4.5 mm, lanceolate, acuminate, unawned; anthers 1.5-2 mm, purple. Caryopses 2-2.5 mm, narrowly elliptic, brownish. 2n = unknown.

Muhlenbergia expansa grows in perennially moist to wet soils in pitcher plant bogs, pine savannahs, and flatwoods, usually in sandy soils and at elevations of 0-300 m. Its primary range is the coastal plain of the southeastern United States.


53.   Muhlenbergia capillaris (Lam.) Trin.
Hairy-Awn Muhly

Plants perennial; cespitose, not rhizomatous. Culms 60-100(150) cm, erect from the base, not conspicuously branched; internodes mostly glabrous, sometimes puberulent below the nodes. Sheaths glabrous or puberulent, basal sheaths rounded, often becoming fibrous, but never spirally coiled, at maturity; ligules 1.8-5(10) mm, membranous, firm, strongly decurrent, obtuse; blades 10-35(80) cm long, 2-4 mm wide, flat or involute, smooth abaxially, scabrous adaxially. Panicles 15-50(60) cm long, 5-30(41) cm wide, longer than wide, diffuse; primary branches 2-20 cm, capillary, diverging 30-100° from the rachises, naked basally, lower branches with 5-20 spikelets; pedicels 10-40(50) mm, longer than the spikelets, capillary, flexible. Spikelets 3-5 mm, usually purple, occasionally green, brown, or stramineous. Glumes subequal, (0.3)1-1.5(2) mm, usually less than 1/2 as long as the lemmas, glabrous; lower glumes 1-veined, usually unawned, rarely awned, awns 1-3 mm; upper glumes1-veined, rarely 3-veined, acute to acuminate, often erose, usually unawned, rarely awned, awns 1-3(5) mm; lemmas 3-5 mm, lanceolate, not shiny, calluses shortly pubescent, apices scabrous, acuminate, sometimes with 2 setaceous teeth, teeth to 1 mm, unawned or awned, awns 2-13(18) mm, clearly demarcated from the lemma bodies; paleas 2-4.5 mm, lanceolate, acuminate, usually unawned; anthers 1.5-2 mm, purple. Caryopses 2-2.5 mm, narrowly elliptic, brownish. 2n = unknown.

In the southeastern United States, Muhlenbergia capillaris usually grows in rocky or clay soils in open woodlands and savannahs and on calcareous outcrops, at elevations of 0-500 m. In the northeastern states, it is also found on diabase and sandstone outcrops and ridges. Its native range includes the southeastern United States, Bahamas, and possibly various Caribbean islands. It is also grown as an ornamental.

Muhlenbergia capillaris resembles M. reverchonii in many respects, but differs it is dull, apically scabrous lemmas.


54.   Muhlenbergia sericea (Michx.) P.M. Peterson
Dune Hairgrass, Purple Muhly

Plants perennial; cespitose, not rhizomatous. Culms 70-140(160) cm, erect from the base, not conspicuously branched; internodes mostly glabrous, sometimes puberulent below the nodes. Sheaths glabrous or puberulent, sheaths rounded near the base, rarely becoming fibrous at maturity, not becoming spirally coiled when old; ligules 4-8(10) mm, membranous, firm, strongly decurrent, obtuse; blades 35-100 cm long, 1-3 mm wide, usually involute, smooth abaxially, scabrous adaxially. Panicles 20-60(70) cm long, 15-30(40) cm wide, longer than wide, diffuse; primary branches 2-20 cm, capillary, diverging 30-100° from the rachises, naked basally, lower branches with 5-20 spikelets; pedicels 4-50 mm, longer than the spikelets, capillary, divergent, stiff or flexible. Spikelets 3-5 mm, mostly purplish. Glumes subequal, (0.3)1-2 mm (excluding the awns), less than 1/2 as long as the lemmas, glabrous; lower glumes 1-veined, awned, awns 0.5-10 mm; upper glumes 1-veined (rarely 3-veined), acute to acuminate, often erose, awned, awns 2-25 mm; lemmas 3-5 mm, lanceolate, calluses shortly pubescent, apices acuminate, with 2 setaceous teeth, teeth 1-5 mm, awned from between the teeth, awns 8-35 mm, clearly demarcated from the lemma bodies; paleas 2-4.5 mm, lanceolate, acuminate, veins usually extending into awns to 2 mm; anthers 1.5-2 mm, purple. Caryopses 2-2.5 mm, narrowly elliptic, brownish. 2n = unknown.

Muhlenbergia sericea grows in sandy maritime habitats on the barrier islands and in coastal woodlands of the southeastern United States, at elevations of 0-50 m. It is available as an ornamental, sometimes under the name 'Purple Muhly'.


55.   Muhlenbergia reverchonii Vasey & Scribn.
Seep Muhly

Plants perennial; cespitose, not rhizomatous, typical bunch grasses in appearance. Culms 40-80 cm, stiffly erect from the base, not conspicuously branched; internodes glabrous, sometimes puberulent below the nodes. Sheaths shorter than the internodes, smooth or scabridulous, basal sheaths rounded, not becoming spirally coiled when old; ligules (2)4-7(9) mm, firmer near the base, obtuse, lacerate; blades 8-35 cm long, 1-2 mm wide, flat or involute, filiform, glabrous abaxially, densely hirtellous adaxially. Panicles 10-20(30) cm long, 4-15 cm wide, about as wide as long, loosely contracted to open but not diffuse; primary branches 1.4-10 cm, capillary, diverging up to 80° from the rachises, scabridulous, naked basally, lower branches with 5-15(20) spikelets; pedicels 3-25 mm, longer than the spikelets, capillary, stiff, or flexuous. Spikelets 3.5-5 mm, stramineous or brownish to purplish. Glumes subequal, 1-3 mm, shorter than the florets, hyaline, mostly sparsely hirtellous, apices glabrous, 1-veined (sometimes faintly so), acute, occasionally mucronate, mucros shorter than 0.7 mm; lemmas 3.5-5 mm, narrowly lanceolate, calluses hairy, hairs to 0.5 mm, lemma bodies glabrous and smooth, apices scabridulous, acuminate, awned, awns 0.5-4(6) mm, clearly demarcated from the lemma bodies; paleas 3.5-5 mm, narrowly lanceolate, mostly glabrous; anthers 1.1-2 mm, yellowish to purplish. Caryopses 2-2.4 mm, fusiform, brownish. 2n = 20.

Muhlenbergia reverchonii grows on calcareous rocky slopes,flats, and limestone rock outcrops, at elevations of 150-650 m. It is restricted to Oklahoma and Texas.

Muhlenbergia reverchonii resembles M. capillaris and M. setifolia in many respects, but differs from the former in its smooth and shiny lemmas, and from the latter in its wider panicles, spreading panicle branches, acute glumes, and more shortly awned lemmas.


56.   Muhlenbergia rigida (Kunth) Trin.
Purple Muhly

Plants perennial; cespitose, not rhizomatous. Culms 40-100 cm, erect, not conspicuously branched; internodes mostly smooth, sometimes scabridulous below the nodes. Sheaths longer than the internodes, smooth or scabridulous, basal sheaths rounded, not becoming spirally coiled when old; ligules (1)3-12(15) mm, firmer basally than distally, obtuse to acute, often lacerate; blades 12-35 cm long, 1-3 mm wide, flat or involute, smooth or scabridulous abaxially, scabridulous or hirtellous adaxially. Panicles 10-35 cm long, 2-5(12) cm wide, loosely contracted to open, purplish; primary branches 0.4-10 cm, lax, capillary, usually appressed to ascending, occasionally diverging up to 80° from the rachises, naked basally; pedicels 1-10 mm. Spikelets 3.5-5 mm, purplish. Glumes equal, 1-1.7(2) mm, exceeded by the florets, usually glabrous, sometimes mostly hirtellous but glabrous distally, 1-veined, obtuse to subacute, unawned; lemmas 3.5-5 mm, narrowly lanceolate, purplish, calluses hairy, hairs to 0.5 mm, lemma bodies scabridulous to scabrous, apices acuminate, awned, awns 10-22 mm, clearly demarcated from the lemma bodies, flexuous; paleas 3.5-5 mm, narrowly lanceolate, scabridulous, acuminate; anthers 1.7-2.3 mm, purplish. Caryopses 2-3.5 mm, fusiform, brownish. 2n = 40, 44.

Muhlenbergia rigida grows on rocky slopes, ravines, and sandy, gravelly slopes derived from granitic and calcareous substrates, at elevations of 1200-2200 m. It is often a common upland bunchgrass, and is also grown as an ornamental plant.

Muhlenbergia rigida grows in two disjunct areas: the southwestern United States south to Chiapas, Mexico, and in Ecuador, Peru, Bolivia, and Argentina. It differs from M. setifolia and M. reverchonii in its purplish, scabridulous to scabrous lemmas.


57.   Muhlenbergia elongata Scribn. ex Beal
Sycamore Muhly

Plants perennial; cespitose, not rhizomatous. Culms 40-120 cm, erect, not conspicuously branched; internodes mostly smooth, sometimes scabridulous below the nodes. Sheaths longer than the internodes, smooth or scabridulous, rounded towards the base, not becoming spirally coiled when old; ligules 2-8 mm, firm below, membranous distally, obtuse to acute; blades 15-50 cm long, 0.3-1.5 mm wide, flat to involute, smooth or scabridulous abaxially, hirtellous adaxially. Panicles 15-50 cm long, 1-7 cm wide, loosely contracted, not dense; primary branches 1-8 cm, appressed or diverging up to 30° from the rachises, naked basally; pedicels 1.3-8 mm, hispidulous. Spikelets 3-4.2 mm. Glumes subequal, 2-3 mm, exceeded by the florets, glabrous below, minutely pubescent or scabridulous distally, 1-veined, acuminate to acute, unawned or awned, awns to 1.6 mm; lemmas 2.8-4.2 mm, narrow, lanceolate, calluses hairy, hairs to 1 mm, lemma bodies glabrous and smooth below, scabridulous distally, apices acuminate, awned, awns 8-40 mm, straight to flexuous, demarcation of the awns from the lemma bodies not evident; paleas 2.8-4.2 mm, narrowly lanceolate, glabrous, acuminate; anthers 1.4-2.2 mm, yellow. Caryopses 2-2.2 mm, fusiform, brownish. 2n = unknown.

Muhlenbergia elongata grows on rock outcrops, cliffs, canyon walls, and moist rock walls, on rhyolitic and volcanic conglomerates, at elevations of 850-2100 m. It extends south from Arizona into northern Mexico.


58.   Muhlenbergia setifolia Vasey
Curlyleaf Muhly

Plants perennial; cespitose, not rhizomatous. Culms 30-80 cm, slightly decumbent basally, erect above, not conspicuously branched, branches, when present, not geniculate and widely divergent; internodes mostly glabrous, sometimes hirtellous below the nodes. Sheaths shorter than the internodes, glabrous, margins whitish, rounded towards the base, not becoming spirally coiled when old; ligules 4-7(10) mm, acuminate, lacerate; blades 5-20(25) cm long, 0.2-1.2 mm wide, tightly involute, arcuate, scabrous abaxially, scabrous or hirtellous adaxially. Panicles 8-20(25) cm long, 2-5 cm wide, loosely contracted; primary branches 0.5-7 cm, capillary, diverging up to 70° from the rachises, naked basally; pedicels 3-20 mm. Spikelets 3.5-5 mm, stramineous to brown or purplish. Glumes subequal, 1.5-2.5 mm, shorter than the florets, thin, hyaline, glabrous; lower glumes without veins, truncate or obtuse, often toothed or notched; upper glumes 1-veined or veinless, obtuse to acute, often mucronate, mucros shorter than 0.7 mm; lemmas 3.5-5 mm, narrowly lanceolate, calluses hairy, hairs to 0.6 mm, lemma bodies glabrous, smooth, shiny, apices acuminate, awned, awns 10-30 mm, clearly demarcated from the lemma bodies, flexuous; paleas 3.5-5 mm, narrowly lanceolate, glabrous, acuminate; anthers 2-2.6 mm, greenish. Caryopses 2.4-3.2 mm, fusiform, brownish. 2n = 40.

Muhlenbergia setifolia grows on calcareous rocky slopes, rock outcrops, and in desert grasslands, at elevations of 1000-2250 m. Its range extends from the southwestern United States into northern Mexico. It is similar to M. reverchonii, but differs in its narrower panicles, less widespread panicle branches, truncate to obtuse glumes, and longer lemma awns.


59.   Muhlenbergia palmeri Vasey
Palmer's Muhly

Plants perennial; cespitose, not rhizomatous. Culms 50-100 cm tall, 2-4 mm thick, erect, rounded near the base, not conspicuously branched, not rooting at the lower nodes; internodes mostly glabrous, sometimes puberulent below the nodes. Sheaths longer than the internodes, smooth or scabridulous, not becoming spirally coiled when old; ligules 1-3 mm, firm to membranous, truncate, ciliolate; blades 15-50 cm long, 1-3.5 mm wide, flat to involute, smooth or scabridulous abaxially, scabrous adaxially. Panicles 15-35 cm long, 0.5-2(3) cm wide; primary branches 0.5-8 cm, appressed; pedicels 1-6 mm, hispidulous. Spikelets 3-4.3 mm, yellowish-brown to purplish. Glumes subequal, (1.7)2-3.1 mm, about 3/4 as long as the florets, scabridulous distally, 1-veined, apices acute to acuminate, awned, awns to 1.5 mm; lemmas 3-4.3 mm, lanceolate, calluses hairy, hairs to 1.5 mm, lemma bodies scabridulous, apices acuminate, awned, awns 3-10 mm, straight; paleas 2.9-4.2 mm, lanceolate, scabridulous, acute to acuminate; anthers 1.5-2.5 mm, yellow to purple-tinged. Caryopses 2-3 mm, fusiform, brownish. 2n = unknown.

Muhlenbergia palmeri grows in rocky drainages and in sandy soil along creeks, at elevations of 1000-2100 m. Its range extends from southern Arizona into northern Mexico.


60.   Muhlenbergia lindheimeri Hitchc.
Lindheimer's Muhly

Plants perennial; cespitose, not rhizomatous. Culms 50-150 cm, stout, erect, not rooting at the lower nodes; internodes mostly glabrous, sometimes puberulent below the nodes. Sheaths shorter or longer than the internodes, glabrous, basal sheaths laterally compressed, keeled, not becoming spirally coiled when old; ligules 10-35 mm, firm and brown basally, membranous distally, acuminate; blades 25-55 cm long, 2-5 mm wide, flat or folded, firm, scabridulous abaxially, scabrous and shortly pubescent adaxially. Panicles 15-50 cm long, 0.6-3 cm wide, often purplish-tinged; primary branches 0.5-7 cm, appressed or strongly ascending, rarely spreading as much as 20° from the rachises; pedicels 0.5-1.2 mm, scabrous. Spikelets 2.4-3.5 mm, light grayish. Glumes equal, 2-3.5 mm, shorter than or equal to the florets, scabrous or smooth, 1-veined, obtuse to acute, occasionally bifid and the teeth to 0.3 mm, unawned, rarely mucronate, mucros less than 0.2 mm; lemmas 2.4-3.5 mm, lanceolate, scabrous or smooth, rarely puberulent near the base, apices obtuse to acute, unawned or awned, awns to 4 mm, straight; paleas 2.4-3.5 mm, lanceolate, obtuse; anthers 1.1-1.5 mm, purplish. Caryopses 1.2-1.6 mm, fusiform, reddish-brown. 2n = 20, 26.

Muhlenbergia lindheimeri grows in sandy draws to rocky, calcareous soils, generally in open areas, at elevations of 150-500 m. It is an uncommon species throughout its range, which includes northern Mexico in addition to southern Texas, but it is also grown as an ornamental. It differs from the closely related M. longiligula in its compressed-keeled basal sheaths, grayish spikelets, and, when present, bifid glume apices.


61.   Muhlenbergia dubia E. Fourn.
Pine Muhly

Plants perennial; densely cespitose, not rhizomatous. Culms 30-100 cm, erect, rounded near the base, not rooting at the lower nodes; internodes glabrous for most of their length, minutely pubescent to hirtellous below the nodes. Sheaths longer than the internodes, smooth or scabridulous, not becoming spirally coiled when old; ligules 4-10 mm, membranous, firm, acute, lacerate; blades 10-60 cm long, 1-2 mm wide, usually involute (occasionally flat), scabrous abaxially, hispidulous adaxially. Panicles 10-40 cm long, 0.6-2.4 cm wide, contracted, grayish-green; primary branches 0.2-7 cm, diverging up to 40° from the rachises, stiff, spikelet-bearing to the base; pedicels 0.1-6 mm, strongly divergent, hispidulous. Spikelets 3.8-5 mm, grayish-green. Glumes equal, (1.8)2-3 mm, shorter than the florets, glabrous and smooth proximally, scabridulous distally, faintly 1-veined, acute; lemmas 3.8-5 mm, narrowly lanceolate, calluses hairy, hairs to 0.5 mm, lemma bodies glabrous and smooth below, scabrous distally, apices acuminate, unawned or awned, awns to 6 mm, straight; paleas 3.8-5 mm, narrowly lanceolate, glabrous below, acuminate; anthers 1.5-2.2 mm, greenish. Caryopses 2.5-3.5 mm, fusiform, brownish. 2n = 40, 50.

Muhlenbergia dubia grows on steep slopes, ridge tops, limestone rock outcrops, and along draws, at elevations of 1500-2300 m. Its range extends into northern Mexico. It resembles M. rigens but differs in having looser, contracted (but not spikelike) panicles, longer ligules, olivaceous anthers, and generally longer lemmas.


62.   Muhlenbergia rigens (Benth.) Hitchc.
Deergrass

Plants perennial; cespitose, not rhizomatous. Culms (35)50-150 cm tall, to 5 mm thick near the base, stiffly erect, not rooting at the lower nodes; internodes glabrous. Sheaths longer than the internodes, smooth or scabridulous, rounded dorsally, bases somewhat flat and chartaceous; ligules 0.5-2(3) mm, firm, truncate, usually ciliolate; blades 10-50 cm long, 1.5-6 mm wide, flat or involute, stiff, glabrous abaxially, scabrous adaxially. Panicles 15-60 cm long, 0.5-1.2 cm wide, spikelike, dense, grayish-green, often interrupted below; primary branches 0.2-4 cm, appressed; pedicels 0.2-3 mm, hispidulous, strongly divergent. Spikelets 2.4-4 mm. Glumes subequal, 1.8-3.2 mm, almost as long as the florets, scabrous to scabridulous, 1-veined, usually acute or obtuse, occasionally acuminate or notched, occasionally mucronate, mucros to 0.6 mm; lemmas 2.4-4 mm, lanceolate, pubescent on the calluses, lower 1/6 of the margins, and midveins, hairs to 0.4 mm, apices scabrous, acute or obtuse, unawned, rarely mucronate, mucros to 1 mm; paleas 2.3-3.8 mm, lanceolate, acute; anthers 1.3-1.8 mm, yellow to purple. Caryopses 1.8-2.2 mm, fusiform, brownish. 2n = 40.

Muhlenbergia rigens grows in sandy washes, gravelly canyon bottoms, rocky drainages, and moist, sandy slopes, often along small streams, at elevations of 90-2500 m. Its geographic range extends to central Mexico. It is available commercially as an ornamental.

Muhlenbergia rigens is similar to M. dubia, but differs in having tighter, spikelike panicles, shorter ligules, yellow or purplish anthers, and shorter lemmas, but differs in having tighter, spikelike panicles, shorter ligules, yellow or purplish anthers, and shorter lemmas.


63.   Muhlenbergia depauperata Scribn.
Sixweeks Muhly

Plants annual; tufted. Culms 3-15 cm; internodes mostly scabridulous or pubescent, pubescent or strigose below the nodes. Sheaths often longer than the internodes, somewhat inflated, smooth or scabrous, keeled, margins scarious, not flattened, papery, or spirally coiled when old; ligules1.4-2.5 mm, membranous, acute, with lateral lobes; blades 1-3 cm long, 0.6-1.5 mm wide, flat or involute, scabrous to strigose, midveins and margins thickened, whitish. Panicles 2.5-8.5 cm long, 0.5-0.7 cm wide, contracted; primary branches 1-2.2 cm, appressed, spikelet-bearing to the base, spikelets borne in subsessile-pedicellate pairs; longer pedicels 3-6 mm, scabrous; disarticulation beneath the spikelet pairs. Spikelets 2.5-5.1 mm, appressed. Glumes 2.3-5.1 mm, equaling or exceeding the florets; lower glumes 2.3-4 mm, subulate, 2-veined, minutely to deeply bifid, teeth aristate or with awns to 1.3 mm; upper glumes 3-5.1 mm, lanceolate, 1-veined, entire, acuminate; lemmas 2.5-4.5 mm, narrowly lanceolate, light greenish-brown to purplish, scabrous, appressed-pubescent on the margins and midveins, apices acuminate, awned, awns 6-15 mm, stiff; paleas 2.4-3.6 mm, lanceolate, intercostal region appressed-pubescent, apices acuminate; anthers 0.5-0.8 mm, purplish to yellowish. Caryopses 1.5-2.3 mm, narrowly fusiform, brownish. 2n = 20.

Muhlenbergia depauperata grows in gravelly flats, rock outcrops, exposed bedrock, and sandy banks, in grama grassland associations, usually on soils derived from calcareous parent materials, at elevations of 1530-2400 m. Its range extends from the southwestern United States to southern Mexico.

Muhlenbergia depauperata and M. brevis share several features with Lycurus: spikelets borne in pairs, 2-veined and 2-awned lower glumes, 1-veined and awned upper glumes, acuminate, awned lemmas with short pubescence along the margins, and pubescent paleas.


64.   Muhlenbergia brevis C.O. Goodd.
Short Muhly

Plants annual; tufted. Culms 3-20 cm. Sheaths often longer than the internodes, somewhat inflated, smooth or scabrous; ligules 1-3 mm, membranous, acute, lacerate, sometimes with lateral lobes; blades 1-4.5 cm long, 0.8-2 mm wide, flat to involute, scabrous to strigose, midveins and margins thickened, whitish. Panicles 3-11.5 cm long, 0.8-1.8 cm wide, contracted; primary branches 1-3.7 cm, closely appressed, spikelets usually in subsessile-pedicellate pairs; pedicels 0.2-8 mm, stout, closely appressed, scabrous; disarticulation beneath the spikelet pairs. Spikelets 2.5-6 mm. Glumes to 2/3 as long as the lemmas; lower glumes 2-3.5 mm, subulate, 2-veined, minutely to deeply bifid, with 2 aristate teeth or awns to 1.8 mm; upper glumes 2.4-4 mm, entire, acuminate to attenuate, 1-veined, awned, awns to 2 mm; lemmas 3.5-6 mm, narrowly lanceolate, light greenish-brown to purplish, scabrous, appressed-pubescent on the margins and midveins, apices acuminate, often bifid, awned, awns usually 10-20 mm, stiff; paleas 4-6 mm, narrowly lanceolate, intercostal region appressed-pubescent, apices acuminate; anthers 0.5-0.9 mm, purplish to yellowish. Caryopses 2-2.8 mm, narrowly fusiform, brownish. 2n = 20.

Muhlenbergia brevis grows on rocky slopes, gravelly flats, and rock outcrops, particularly those derived from calcareous parent materials, at elevations of 1700-2500 m, in grama grasslands, pinyon-juniper woodlands, and pine-oak woodlands. Its range extends from the southwestern United States to central Mexico.

Like Muhlenbergia depauperata, M. brevis shares several features with Lycurus, notably the paired spikelets with 2-veined and 2-awned lower glumes, 1-veined and awned upper glumes, acuminate, awned lemmas with shortly pubescent margins, and pubescent paleas.


65.   Muhlenbergia sinuosa Swallen
Marshland Muhly

Plants annual; delicate. Culms 12-50 cm, erect to geniculate; internodes mostly glabrous and smooth or scabridulous, scabridulous or strigulose below the nodes. Sheaths usually longer than the internodes, glabrous, smooth or scabridulous; ligules 1.5-3.1 mm, hyaline, truncate to obtuse, irregularly toothed to lacerate, with lateral lobes that exceed the central portion; blades 2-8.5 cm long, 0.8-2 mm wide, flat, sometimes involute, scabridulous abaxially, shortly pubescent to minutely villous adaxially, midveins prominent abaxially. Panicles 10-26 cm long, 2.8-8 cm wide; primary branches 2.6-7 cm, often capillary, diverging 25-80° from the rachises; pedicels 4-7 mm, usually curved, often through 90° or more. Spikelets 1.4-2 mm. Glumes equal, 0.7-1.2mm, usually conspicuously strigulose, particularly near the margins and apices, 1-veined, acute to obtuse, unawned; lemmas 1.4-2 mm, oblong-elliptic, greenish, sometimes purplish-tinged, shortly appressed-pubescent on the midveins and margins, apices acute or obtuse, unawned; paleas 1.3-1.8 mm, oblong-elliptic, intercostal region sparsely short-pilose or glabrous; anthers 0.6-1.2 mm, olivaceous. Caryopses 0.8-1.2 mm, fusiform, brownish. 2n = 20, 24.

Muhlenbergia sinuosa grows in sandy soil along washes, on open slopes and rocky ledges, and in roadside ditches, at elevations of 1650-2300 m. It is usually found in oak-pine forests, pinyon-juniper woodlands, oak-grama savannahs, and riverine woodlands. Its range extends from the southwestern United States into northern Mexico.


66.   Muhlenbergia minutissima (Steud.) Swallen
Annual Muhly

Plants annual. Culms 5-40 cm, slender, erect; internodes mostly glabrous, scabridulous or smooth, scabridulous or strigulose below the nodes. Sheaths shorter or longer than the internodes, smooth or scabridulous; ligules 1-2.6 mm, hyaline, truncate to obtuse, sometimes with lateral lobes; blades 0.5-4(10) cm long, 0.8-2 mm wide, flat or involute, scabrous abaxially, shortly pubescent adaxially. Panicles 5-16.2(21) cm long, 1.5-6.5 cm wide, open; primary branches 8-42 mm, often capillary, diverging 25-80° from the rachises; pedicels 2-7 mm, straight or curved, but rarely curved as much as 90°. Spikelets 0.8-1.5 mm. Glumes sparsely strigulose, at least near the apices, 1-veined; lower glumes 0.5-0.8 mm, obtuse to acute; upper glumes 0.6-0.9 mm, broader than the lower glumes, obtuse; lemmas 0.8-1.5 mm, lanceolate, brownish to purplish, glabrous or the midveins and margins appressed-pubescent, apices obtuse to subacute, unawned; paleas 0.8-1.4 mm, shortly pubescent or glabrous; anthers 0.2-0.7 mm, purplish. Caryopses 0.6-0.9 mm, fusiform to elliptic, brownish. 2n = 60, 80.

Muhlenbergia minutissima grows in sandy and gravelly drainages, rocky slopes, flats, road cuts, and open sites. It is usually found in yellow pine and oak-pine forests, pinyon-juniper woodlands, thorn-scrub forests, and oak-grama savannahs, at elevations of 1200-3000 m. Its range extends from the western United States to southern Mexico.


67.   Muhlenbergia texana Buckley
Texas Muhly

Plants annual; slender. Culms 10-35 cm, erect; internodes strigulose. Sheaths shorter or longer than the internodes, strigulose; ligules 0.9-2.5 mm, hyaline, acute to obtuse, irregularly toothed to lacerate; blades 1-6(8) cm long, 0.8-2 mm wide, flat or involute, scabrous and sparsely strigulose on both surfaces. Panicles 9-21 cm long, 2-7 cm wide; primary branches 12-60 mm, occasionally capillary, narrowly ascending or diverging up to 70° from the rachises; pedicels 2-7 mm, usually longer than the florets, straight to somewhat curved, rarely bent as much as 90°; disarticulation above the glumes. Spikelets 1.3-2 mm. Glumes sparsely strigulose, particularly on the margins, 1-veined, acute to acuminate; lower glumes 0.8-1.2 mm; upper glumes 0.9-1.5 mm, bases slightly wider than the lower glumes; lemmas 1.3-2 mm, lanceolate,purplish to brown, shortly appressed-pubescent on the lower 1/2 of the midveins and margins, apices acute to acuminate, awned, awns 0.1-1(2) mm; paleas 1.3-2 mm, oblong-elliptic, minutely appressed-pubescent on the lower 1/2, apices acute; anthers 0.4-0.5 mm, purplish. Caryopses 0.8-1 mm, fusiform, brownish. 2n = 40.

Muhlenbergia texana grows on open slopes, in sandy, gravelly drainages, and on rock outcrops, at elevations of 1200-2750 m. Its range extends from the southwestern United States into northwestern Mexico.


68.   Muhlenbergia eludens C. Reeder
Gravelbar Muhly

Plants annual. Culms 10-40 cm, erect; internodes mostly glabrous, strigulose below the nodes. Sheaths usually longer than the internodes, scabridulous or puberulent, keeled; ligules 1.5-2.5 mm, membranous, acute, erose; blades (1)2-5.5(8) cm long, 0.8-2 mm wide, usually involute, occasionally flat, scabridulous abaxially, villous adaxially. Panicles 14-24 cm long, 3-7 cm wide, narrowly pyramidal, open; primary branches 2-7 cm, ascending, diverging less than 40° from the rachises; pedicels 1-2(3) mm, usually shorter than the florets, appressed; disarticulation above the glumes. Spikelets 1.7-3 mm. Glumes subequal, 1.3-1.8 mm, sparsely hirsute, 1-veined; lower glumes 1.3-1.6 mm, acuminate, sometimes awned, awns to 0.5 mm; upper glumes 1.4-1.8 mm, wider than the lower glumes, acuminate; lemmas (1.7)1.9-2.5 mm, lanceolate, purplish or yellowish to light brownish, appressed-pubescent on the midveins and margins, hairs to 0.5 mm, apices awned, awns 1.2-3.5 mm, delicate; paleas 1.8-2.4 mm, oblong-elliptic, glabrous; anthers 0.4-0.6 mm, purplish. Caryopses 1.3-2.3 mm, fusiform to dorsally compressed, light brownish. 2n = 40.

Muhlenbergia eludens grows in open sandy gullies, washes, rocky slopes, and roadsides. It is found at elevations of 1700-2450 m in the southwestern United States and northwestern Mexico.


69.   Muhlenbergia fragilis Swallen
Delicate Muhly

Plants annual. Culms 10-38 cm, erect or spreading; internodes mostly glabrous, smooth or scabridulous, scabrous or strigulose below the nodes. Sheaths often longer than the internodes, scabridulous, margins hyaline; ligules 1-3 mm, hyaline, obtuse, irregularly toothed to lacerate, with lateral lobes; blades 1-10 cm long, 0.4-2 mm wide, flat, scabrous abaxially, strigulose adaxially, margins and midveins thickened basally, whitish. Panicles 10-24 cm long, 3.5-11 cm wide, diffuse; primary branches 2.2-6.2 cm long, about 0.1 mm thick, diverging 80-100° from the rachises, straight; pedicels 6-10 mm long, about 0.02 mm thick, delicate; disarticulation above the glumes. Spikelets 1-1.2 mm, appressed to slightly divergent. Glumes equal to subequal, 0.5-1 mm, glabrous throughout or obscurely puberulent, hairs about 0.06 mm, 1-veined, obtuse or subacute; lemmas 1-1.2 mm, oblong-elliptic, purplish to light brownish, not mottled, glabrous or densely appressed-puberulent on the margins and midveins, apices obtuse, unawned; paleas 0.9-1.2 mm, oblong-elliptic; anthers 0.3-0.5 mm, purplish. Caryopses 0.7-0.9 mm, elliptic, reddish-brown. 2n = 20.

Muhlenbergia fragilis grows on rocky talus slopes, cliffs, canyon walls, road cuts, and sandy slopes, often over calcareous parent materials, at elevations of 480-2200 m. It is usually found in oak-grama savannahs, thorn scrub forests, oak-yellow pine forests, and pinyon-juniper woodlands. Its range extends from the southwestern United States to southern Mexico.

Populations may have individual plants with completely glabrous lemmas or may consist entirely of such plants. This morphological variation is not correlated with any distributional or habitat characteristics.


70.   Muhlenbergia ramulosa (Kunth) Swallen
Green Muhly

Plants annual. Culms (3)5-25 cm, erect, branching, but not rooting, basally; internodes glabrous, mostly smooth, sometimes scabridulous below the nodes. Sheaths usually shorter than the internodes, glabrous, smooth or scabridulous; ligules 0.2-0.5 mm, hyaline, truncate, ciliate, without lateral lobes; blades 0.5-3 cm long, 0.8-1.2 mm wide, involute or flat, glabrous abaxially, puberulent adaxially. Panicles (1)2-9 cm long, 0.6-2.7 cm wide, open, ovoid or deltoid, spikelets sparse; primary branches (0.5)1-3.2 cm long, about 0.1 mm thick, ascending, spreading 20-100° from the rachises; pedicels 1-3 mm long, 0.5-1.5 mm thick, stiff. Spikelets 0.8-1.3 mm, appressed or divaricate. Glumes equal, 0.4-0.7 mm, glabrous, 1-veined, obtuse or subacute, unawned; lemmas 0.8-1.3 mm, oval, plump, mottled with greenish-black and greenish-white or ochroleucous patches, glabrous or shortly appressed-pubescent on the margins and midveins, apices acute, unawned; paleas 0.7-1.3 mm, oval; anthers 0.2-0.3 mm, purplish. Caryopses 0.5-1 mm, elliptic, brownish. 2n = 20.

Muhlenbergia ramulosa grows in open, well-drained areas including slopes, sandy meadows, washes, gravelly road cuts, and rock outcrops in yellow pine-oak forests and in open meadows of pine-fir forests, at elevations of 2100-3500 m. Its range includes the southwestern United States, Mexico, Guatemala, Costa Rica, and Argentina.