13.01 HORDEUM L.
Roland von Bothmer
Claus Baden†
Niels H. Jacobsen

Plants summer or winter annuals or perennials; cespitose, sometimes shortly rhizomatous. Culms to 135(150) cm, erect, geniculate, or decumbent; nodes glabrous or pubescent. Sheaths open, pubescent or glabrous; auricles present or absent; ligules hyaline, truncate, erose; blades flat to more or less involute, more or less pubescent on both sides. Inflorescences usually spikelike racemes, sometimes spikes, all customarily called spikes, with 3 spikelets at each node, central spikelets usually sessile, sometimes pedicellate, pedicels to 2 mm, lateral spikelets usually pedicellate, pedicels curved or straight, sometimes all 3 spikelets sessile in cultivated plants; disarticulation usually in the rachises, the spikelets falling in triplets, cultivated forms generally not disarticulating. Spikelets with 1 floret; glumes awnlike, usually exceeding the floret. Lateral spikelets usually sterile or staminate, often bisexual in cultivated forms; florets pedicellate, usually reduced; lemmas awned or unawned. Central spikelets bisexual; florets sessile; rachillas prolonged beyond the floret; lemmas ovate, glabrous to pubescent, 5-veined, usually awned, rarely unawned; paleas almost equal to the lemmas, narrowly ovate, keeled; lodicules 2, broadly lanceolate, margins ciliate; anthers 3, usually yellowish. Caryopses usually tightly enclosed in the lemma and palea at maturity. 2n = 14, 28, 42. Name from the old Latin name for barley.

Hordeum is a genus of 32 species that grow in temperate and adjacent subtropical areas, at elevations from 0–4500 m. The genus is native to Eurasia, the Americas, and Africa, and has been introduced to Australasia. The species are confined to rather moist habitats, even on saline soils. The annual species occupy seasonally moist habitats that cannot sustain a continuous grass cover.

Some species of Hordeum, such as H. marinum and H. murinum, are cosmopolitan weeds. Hordeum vulgare is widely cultivated for feed, malt, and flour. Archeological records suggest that Hordeum and Triticum were two of the earliest domesticated crops.

Eleven species of Hordeum grow in the Flora region: six are native, three are established weeds, and two are cultivated and occasionally persist as weeds. Hordeum secalinum has been reported from the Flora region, but the reports are based on misidentifications.

Four different haplomes are present in Hordeum. Hordeum vulgare and H. bulbosum have the I genome (often called the H genome by plant breeders), North American diploid species are based on the H genome, diploid H. marinum on the X genome, and diploids in the H. murinum group on the Y genome. Relationships among the polyploid taxa are complex (Jakob and Blattner 2006).

Spike measurements and lemma lengths, unless stated otherwise, do not include the awns.

 

SELECTED REFERENCES Baum, B.R. 1978. The status of Hordeum brachyantherum in eastern Canada, with related discussions. Canad. J. Bot. 56:107–109; Baum, B.R. and L.G. Bailey. 1990. Key and synopsis of North American Hordeum species. Canad. J. Bot. 68:2433–2442; Blattner, F.R. 2006. Multiple intercontinental dispersals shaped the distribution area of Hordeum (Poaceae). New Phytol. 169:603–614; Bothmer, R. von, N. Jacobsen, C. Baden, R.B. Jørgensen, and I. Linde-Laursen. 1995. An Ecogeographical Study of the Genus Hordeum, ed. 2. Systematic and Ecogeographic Studies on Crop Genepools No. 7. International Board of Plant Genetic Resources, Rome, Italy. 129 pp.; Bothmer, R. von, N. Jacobsen, and R.O. Seberg. 1993. Variation and taxonomy in Hordeum depressum and in the H. brachyantherum complex (Poaceae). Nordic J. Bot. 13:3–17; Jakob, S.S. and F.R. Blattner. 2006. A chloroplast genealogy of Hordeum (Poaeae): Long-term persisting haplotypes, incomplete lineage sorting, regional extinction, and the consequences for phylogenetic inference. Mol. Biol. Evol. 23:1602–1612; Moyer, J.R. and A.L. Boswall. 2002. Tall fescue or creeping foxtail suppresses foxtail barley. Canad. J. Pl. Sci. 82:89–92; Petersen, G. and O. Seberg. 2003. Phylogenetic analyses of the diploid species of Hordeum (Poaceae) and a revised classification of the genus. Syst. Bot. 28:293–306.

 

For an interactive dichotomous key, click here; for an interactive, multientry key, click here.

 

1. Plants perennial ... 2
1. Plants annual ... 6
2. Culms usually with a bulbous swelling at the base; auricles to 5.5 mm long, well developed ... H. bulbosum
2. Culms not bulbous-based; auricles absent or no more than 1 mm long ... 3
3. Glumes of the central spikelet flattened near the base ... H. arizonicum (in part)
3. Glumes of the central spikelet usually setaceous throughout, rarely flattened near the base ... 4
4. Glumes 15–85 mm long, divergent to strongly divergent at maturity ... H. jubatum (in part)
4. Glumes 7–19 mm long, divergent or not at maturity ... 5
5. Anthers of the central spikelet 0.8–4 mm long; auricles absent ... H. brachyantherum
5. Anthers of the central spikelet 3.5–5 mm long; auricles present on the basal leaves ... H. secalinum
6. Auricles to 8 mm long, well developed even on the upper leaves; lemmas of the lateral florets 6–15 mm long ... 7
6. Auricles usually absent or to 0.3 mm long; lemmas of the lateral florets 1.7–8.5 mm long ... 8
7. Rachises disarticulating at maturity; glumes of the central spikelets ciliate; lemmas of the central florets to 2 mm wide, with awns 20–40 mm long; lateral spikelets staminate ... H. murinum
7. Rachises usually not disarticulating at maturity; glumes of the central spikelets pubescent; lemmas of the central florets at least 3 mm wide, unawned or with awns 30–180 mm long; usually 1 or both lateral spikelets at a node seed-forming ... H. vulgare
8. Glumes bent, strongly divergent at maturity ... 9
8. Glumes straight, ascending to slightly divergent at maturity ... 10
9. Glumes of the central spikelets not flattened, (15)35–85 mm long ... H. jubatum (in part)
9. Glumes of the central spikelets slightly flattened towards the base, 11–28 mm long ... H. arizonicum (in part)
10. Lemmas of the lateral spikelets with awns 3–8 mm long ... H. marinum
10. Lemmas of the lateral spikelets unawned or with awns no more than 3 mm long ... 11
11. Glumes of the central spikelets setaceous to slightly flattened near the base ... 12
11. Glumes of the central spikelets distinctly flattened near the base ... 13
12. Spikes 4–8 mm wide; lemmas of the central spikelets with awns 3–12 mm long; ligules 0.3–0.8 mm long ... H. depressum
12. Spikes 6–20 mm wide; lemmas of the central spikelets with awns 10–22 mm long; ligules 0.6–1.8 mm long ... H. arizonicum (in part)
13. Lemmas of the lateral spikelets 1.7–4.4 mm long, usually unawned, rarely with awns to 1.2 mm long; sheaths with stripes of hairs ... H. intercedens
13. Lemmas of the lateral spikelets 2.5–5.7 mm long, usually awned, with awns to 1.8 mm long; sheaths glabrous ... H. pusillum

 

1. Hordeum intercedens Nevski
Bobtail Barley

Plants annual; loosely tufted. Culms 5–40 cm, erect to geniculate; nodes usually pubescent. Sheaths with stripes of hairs; ligules 0.3–0.8 mm; auricles usually absent, shorter than 2 mm if present; blades to 9 cm long, to 4 mm wide, both surfaces sparsely to densely hairy, hairs spreading. Spikes 2.5–6.2 cm long, 4–6 mm wide, often partially enclosed at maturity, pale green. Glumes straight, usually slightly divergent at maturity. Central spikelets: glumes to 17 mm long, to 0.8 mm wide basally, distinctly flattened near the base; lemmas 4.5–7.5 mm, usually sparsely pubescent towards the base, glabrous distally, awned, awns 5.6–9.8 mm, often slightly divergent at maturity; anthers 0.6–1.2 mm. Lateral spikelets usually sterile; glumes to 17.5 mm, distinctly flattened near the base; lemmas 1.7–4.4 mm, blunt to acute, usually unawned, rarely awned, awns to 1.2 mm. 2n = 14.

Hordeum intercedens grows in vernal pools and flooded, often saline river beds and alkaline flats. It is restricted to southwestern California, including some of the coastal islands, and northwestern Baja California, Mexico.

 

2. Hordeum pusillum Nutt.
Little Barley

Plants annual; loosely tufted. Culms 10–60 cm, erect, geniculate, or ascending; nodes glabrous. Sheaths glabrous or slightly pubescent; ligules 0.2–0.8 mm; auricles absent; blades to 10.5 cm long, to 4.5 mm wide, sparsely to densely pubescent on both sides. Spikes 2–9 cm long, 3–7 mm wide, erect, often partially enclosed at maturity, pale green. Glumes straight, not divergent at maturity. Central spikelets: glumes 8–17 mm long, 0.5–1.5 mm wide, distinctly flattened near the base; lemmas 5–8.5 mm, usually glabrous, sometimes sparsely to densely pubescent, awned, awns 3.5–9.5 mm; anthers 0.7–1.8 mm. Lateral spikelets usually sterile; glumes to 18 mm; lower glumes distinctly flattened, more or less winged basally; lemmas 2.5–5.7 mm, usually awned, awns to 1.8 mm, rarely unawned; anthers 0.6–1.2 mm. 2n = 14.

Hordeum pusillum grows in open grasslands, pastures, and the borders of marshes, and in disturbed places such as roadsides and waste places, often in alkaline soil. It is native, widespread, and often common in much of the Flora region. Its range extends into northern Mexico, but it is not common there.

 

3. Hordeum depressum (Scribn. & J.G. Sm.) Rydb.
Low Barley

Plants annual; loosely tufted. Culms 10–55 cm, erect; nodes glabrous. Basal sheaths pubescent; ligules 0.3–0.8 mm; auricles absent; blades to 7.5(13.5) cm long, to 4.5 mm wide, sparsely to densely pubescent on both sides. Spikes 2.2–7 cm long, 4–8 mm wide, often partially enclosed at maturity, pale green or with a reddish tinge to the glumes and awns. Glumes straight, ascending to slightly divergent at maturity. Central spikelets: glumes 5.5–20.5 mm long, to 0.5 mm wide, setaceous to slightly flattened near the base; lemmas 5–9 mm, glabrous, awned, awns 3–12 mm; anthers 0.5–1.5 mm. Lateral spikelets sterile or staminate, occasionally bisexual; glumes 5–20 mm; lower glumes slightly flattened near the base; upper glumes setaceous throughout; lemmas 1.8–8.5 mm, unawned or awned, awns to 1 mm. 2n = 28.

Hordeum depressum grows in vernal pools and ephemeral habitats, often in alkaline soil. It is restricted to the western United States.

 

4. Hordeum brachyantherum Nevski

Plants perennial; loosely to densely cespitose. Culms to 90 cm, erect to geniculate, not bulbous; nodes glabrous. Sheaths glabrous or densely pubescent; auricles absent; blades to 19 cm long, to 8 mm wide, glabrous or with hairs on both surfaces, hairs sometimes of mixed lengths. Spikes 3–8.5 cm, green to somewhat purple. Glumes 7–19 mm, ascending to slightly divergent at maturity. Central spikelets: glumes 9–19 mm long, about 0.2 mm wide, setaceous throughout, rarely flattened near the base; lemmas 5.5–10 mm, usually glabrous, rarely pubescent, awned, awns 3.5–14 mm; anthers 0.8–4 mm. Lateral spikelets staminate; glumes 7–19 mm, setaceous; lower glumes sometimes flattened near the base; lemmas rudimentary to well developed, awns to 7.5 mm, rarely absent; anthers 0.8–4 mm. 2n = 14, 28, 42.

Hordeum brachyantherum is native to the Kamchatka Peninsula and western North America, and has been introduced to a few locations in the eastern United States. There is also a small disjunct population in Newfoundland and Labrador that Baum (1978) identified as H. secalinum. Hordeum brachyantherum grows in salt marshes, pastures, woodlands, subarctic woodland meadows, and subalpine meadows.

Two subspecies are recognized here, but there is so much overlap in their morphological variation that unambiguous determination of many specimens is impossible in the absence of a chromosome count. They are sometimes treated as two species.

1. Basal sheaths usually glabrous, sometimes sparsely pubescent; anthers 0.8–3.5 mm long; culms often robust, sometimes slender ... subsp. brachyantherum
1. Basal sheaths usually densely pubescent; anthers 1.1–4 mm long; culms usually slender ... subsp. californicum

Hordeum brachyantherum Nevski subsp. brachyantherum
Meadow Barley, Northern Barley,
Orge à Anthères Courtes, Orge des Prés

Plants densely cespitose. Culms 30–95 cm, often robust, sometimes slender. Basal sheaths usually glabrous, sometimes sparsely pubescent; blades to 19 cm long, to 8 mm wide, both sides usually glabrous, sometimes with hairs to 0.5 mm on both surfaces. Glumes 7–17 mm, usually straight at maturity; lemmas usually awned, awns to 6.5 mm, usually straight at maturity; anthers 0.8–3.5 mm. 2n = 28, 42.

Hordeum brachyantherum subsp. brachyantherum grows in pastures and along streams and lake shores, from sea level to 4000 m. Its range extends from Kamchatka through western North America to Baja California, Mexico. It is also known from disjunct locations in Newfoundland and Labrador and the eastern United Sates. The latter are probably recent introductions; the Newfoundland populations are harder to explain. One population from California is known to be hexaploid.

Hordeum brachyantherum subsp. californicum (Covas & Stebbins) Bothmer, N. Jacobsen & Seberg
California Barley

Plants loosely cespitose. Culms 20–65 cm, usually slender. Basal sheaths usually densely pubescent; blades to 11.5 cm long, to 3.5(5.5) mm wide, usually hairy with spreading hairs of mixed lengths on both sides, rarely glabrous or almost glabrous. Glumes 9–19 mm, usually spreading at maturity; lemmas usually awned, awns to 7.5 mm, usually divergent at maturity; anthers 1.1–4 mm. 2n = 14.

Hordeum brachyantherum subsp. californicum is restricted to California. It grows on dry and moist grass slopes, in meadows and rocky stream beds, along stream margins, and around vernal pools, in oak woodlands and disturbed ground, and in serpentine, alkaline, and granitic soils, up to 2300 m. Records from outside California, and many from inside California, are based on misidentified specimens, usually of H. brachyantherum subsp. brachyantherum.

 

5. Hordeum jubatum L.

Plants perennial, sometimes appearing annual; cespitose. Culms 20–80 cm, geniculate to straight, not bulbous based; nodes glabrous. Sheaths glab-rous or pubescent; ligules to 0.8 mm; auricles absent; blades to 15 cm long, to 5 mm wide, scabrous, sometimes hairy. Spikes 3–15 cm, usually nodding, whitish green to light purplish. Glumes 15–85 mm long, conspicuous, bent, divergent to strongly divergent at maturity. Central spikelets: glumes (15)35–85 mm, setaceous throughout, strongly spreading at maturity; lemmas 4–8.5 mm, glabrous, awned, awns 11–90 mm, straight to ascending; paleas 5.5–8 mm; anthers 0.6–1.2 mm. Lateral spikelets staminate or sterile; glumes 17–83 mm, setaceous; lemmas 4–6.5 mm, awned; awns 2–15 mm, divergent; anthers 1–1.5 mm. 2n = 28.

Hordeum jubatum grows in meadows and prairies around riverbeds and seasonal lakes, often in saline habitats, and along roadsides and in other disturbed sites. It is native from eastern Siberia through most of North America to Mexico, growing at elevations of 0–3000 m. It has been introduced to South America, Europe, and central Asia. It is grown in Russia and other areas outside its native range as an ornamental. In its native range, it is a weedy species.

Hordeum jubatum shows a wide range of variation in almost all characters; most such variation is not taxonomically significant. Hordeum jubatum subsp. intermedium is considered to be a subspecies of H. jubatum because no clear-cut discontinuities exist in the characters used to distinguish it from H. jubatum subsp. jubatum. These plants are fertile.

1. Glumes of the central spikelet 15–35 mm long; lemma awns of the central spikelets 11–35 mm long ... subsp. intermedium
1. Glumes of the central spikelet 35–85 mm long; lemma awns of the central spikelets 35–90 mm long ... subsp. jubatum

Hordeum jubatum subsp. intermedium Bowden
Intermediate Barley

Central spikelets: glumes 15–35 mm, spreading at maturity; lemmas awned, awns 11–35 mm.

Hordeum jubatum subsp. intermedium is most abundant in the dry prairies of the northern Rocky Mountains and northern plains, growing at 0–3000 m. It also grows, as a disjunct, in southern Mexico. It is sometimes treated as a species, either as H. intermedium Hausskn. or H. ×intermedium Hausskn., the latter reflecting a suspected hybrid origin involving H. jubatum and H. brachyantherum.

Hordeum jubatum L. subsp. jubatum
Foxtail Barley, Squirreltail Barley,
Squirreltail Grass, Orge Agréable, Queue d’Écureuil, Orge Queue d’Écureuil

Central spikelets: glumes 35–85 mm, strongly spreading at maturity; lemmas awned, awns 35–90 mm.

Hordeum jubatum subsp. jubatum is the more widespread of the two subspecies, extending from eastern Siberia through most of North America to northern Mexico. Native in western and northern portions of the Flora region, it is considered to be adventive in the eastern and southeastern portion of its range. It grows in moist soil along roadsides and other disturbed areas, as well as in meadows, the edges of sloughs and salt marshes, and on grassy slopes.

 

6. Hordeum arizonicum Covas
Arizona Barley

Plants annual to biennial, perennial under favorable conditions; forming small tufts. Culms 21–75 cm, rarely geniculate, not bulbous; nodes glabrous. Lower sheaths pub-escent; upper sheaths glabrous; ligules 0.6–1.8 mm; auricles absent; blades to 13 cm long, to 4 mm wide, flat, glaucous, both surfaces scabrous, hairy, sometimes only sparsely hairy. Spikes 5–12 cm long, 6–10 mm wide, erect, often partially enclosed at maturity, pale green. Glumes bent, strongly divergent at maturity. Central spikelets: glumes 11–28 mm long, 0.2–0.4 mm wide, flattened near the base, setaceous above the middle; lemmas 5–9 mm, glabrous, awned, awns 10–22 mm; anthers 1–2.2 mm. Lateral spikelets sterile; glumes to 27 mm long, 0.2–0.4 mm wide, flattened near the base; lemmas 2.5–5 mm, unawned or awned, awns to 3 mm, lemma and awn together to 7 mm, the transition from the lemma to the awn gradual. 2n = 42.

Hordeum arizonicum grows in saline habitats, along irrigation ditches, canals, and ponds in the south-western United States and northern Mexico. It is a segmental allopolyploid between H. jubatum and either H. pusillum or H. intercedens.

 

7. Hordeum marinum Huds.

Plants annual; loosely tufted. Culms to 50 cm, straight to geniculate; nodes glabrous. Basal sheaths somewhat hairy; ligules 0.2–0.5 mm; auricles usually absent or to 0.3 mm; blades to 8 cm long, 1–6 mm wide, sparsely to densely hairy on both sides. Spikes 1.5–7 cm long, 5–10(20) mm wide, dense, green or more or less purplish on the awns and glumes; rachises disarticulating at maturity, triplets not breaking up immediately after maturity. Glumes straight, ascending to slightly divergent at maturity. Central spikelets: glumes 14–26 mm long, 0.2–1.1 mm wide basally, setaceous distally; lemmas 5–8 mm, usually smooth or somewhat scabrous, sometimes pubescent, awned, awns 6–18 mm; anthers 0.8–1.3 mm, yellowish. Lateral spikelets sterile; lower glumes setaceous or winged, wings 0.5–2.3 mm wide; upper glumes setaceous; lemmas 4–6 mm, awned, awns 3–8 mm. 2n = 14, 28.

Hordeum marinum is native to Eurasia, where it grows in disturbed habitats. It has become established in similar habitats in western North America, and in scattered locations elsewhere. Two subspecies are recognized; both are found in the Flora region.

1. Lower glumes of the lateral spikelets usually setaceous, not winged ... subsp. gussoneanum
1. Lower glumes of the lateral spikelets with a flattened wing, the wings 0.5–2.3 mm wide ... subsp. marinum

Hordeum marinum subsp. gussoneanum (Parl.) Thell.
Mediterranean Barley, Geniculate Barley

Plants summer annuals. Leaves 1.5–4 mm wide, flat or involute. Lateral spikelets: lower glumes usually setaceous, occasionally a little widened, but not winged. 2n = 14, 28.

Hordeum marinum subsp. gussoneanum grows in grassy fields, waste places, and open ground. It was introduced to North America from the Mediterranean area, and it is now an established weed, especially in western North America.

Hordeum marinum Huds. subsp. marinum
Sea Barley

Plants summer or winter annuals. Leaves 1.5–8 mm wide, usually flat. Lateral spikelets: lower glumes winged on the side towards the central spikelets, wings 0.5–2.3 mm wide. 2n = 14.

Hordeum marinum subsp. marinum is native to Eurasia, where it grows in disturbed habitats. Although it has been reported occasionally from the Flora region, it has not become established.

 

8. Hordeum secalinum Schreb.
False-Rye Barley, Meadow Barley

Plants perennial; loosely cespitose. Culms to 85 cm, erect, usually slender, not bulbous; nodes glabrous. Sheaths, at least the basal sheaths, densely pubescent; auricles to 1 mm, present on the basal leaves; blades flat or involute, surfaces scabrous, densely pilose. Spikes 3–7 cm. Glumes 8–15 mm, setaceous throughout, straight, slightly divergent at maturity. Central spikelets sessile; lemmas 5.7–9.9 mm, glabrous, awned, awns 5–15.4 mm, scabrous; anthers 3.5–5 mm, yellow. Lateral spikelets usually staminate, occasionally bisexual; lemmas 3.7–6.9 mm, usually glabrous, sometimes sparsely pilose, awns 1.4–5.8 mm; anthers 1.7–3.3 mm. 2n = 28.

Hordeum secalinum is native to Europe, where it grows in moist, saline areas, often in coastal meadows. It does not grow in the Flora region; reports from North America (Baum 1978) were based on specimens of Hordeum brachyantherum, from which H. secalinum differs in having auricles on the basal leaves and longer anthers. It is treated here to aid those interested in distinguishing between the two species.

 

9. Hordeum murinum L.

Plants annual; loosely tufted. Culms to 110 cm, usually erect, sometimes almost prostrate; nodes glabrous. Lower sheaths often completely surrounding the culms, glabrous or somewhat pilose; ligules 1–4 mm; auricles to 8 mm, well developed even on the upper leaves; blades to 28 cm, usually flat, occasionally with involute margins, glabrous or sparsely pilose, sometimes scabrous. Spikes 3–8 cm long, 7–16 mm wide, pale green to distinctly reddish, especially the awns; rachises disarticulating at maturity. Central spikelets sessile, florets sessile or pedicellate, pedicels to 2 mm; glumes 11–25 mm long, 0.8–1.8 mm wide, flattened, margins usually distinctly ciliate; lemmas 8–14 mm long, to 2 mm wide, more or less smooth, awned, awns 20–40 mm; lodicules glabrous or with 1+ cilia; anthers 0.2–3.2 mm, gray to yellow, sometimes with purple spots. Lateral spikelets staminate, floret sessile; glumes flattened, margins ciliate; lemmas 8–15 mm, awned, awns 20–50 mm; paleas 8–15 mm; rachillas 2.5–6.5 mm, slender or gibbous, yellow. 2n = 14, 28, 42.

Hordeum murinum is native to Eurasia, where it is a common weed in areas of human disturbance. It is thought to have originated around seasides, sandy riverbanks, and animal watering holes. It is now an established weed in the southwestern Flora region and other scattered locations. The records in Alaska are from the Anchorage area. Prostrate plants are associated with grazing. Three subspecies are recognized.

1. Central spikelets sessile to subsessile; lemmas of the central florets subequal to those of the lateral florets, the awns longer than those of the lateral florets; paleas of the lateral florets almost glabrous ... subsp. murinum
1. Central spikelets pedicellate; lemmas of the central florets from subequal to shorter than those of the lateral florets, the awns from shorter to longer than those of the lateral florets; paleas of the lateral florets scabrous to hairy ... 2
2. Lemmas of the central florets much shorter than those of the lateral florets; paleas of the lateral florets scabrous on the lower 1/2; anthers of the central and lateral florets similar in size ... subsp. leporinum
2. Lemmas of the central florets about equal to those of the lateral florets; paleas of the lateral florets distinctly pilose on the lower 1/2; anthers of the central florets 0.2–0.6 mm long, those of the lateral florets 1.2–1.8 mm long ... subsp. glaucum

Hordeum murinum subsp. glaucum (Steudel) Tzvelev
Smooth Barley

Plants summer annuals. Culms 15–40 cm. Leaves glaucous. Spikes sometimes glaucous, often brownish when mature. Central floret pedicellate; lemmas subequal to those of the lateral florets, awns as long as or longer than those of the lateral florets; anthers 0.2–0.6 mm, much shorter than those of the lateral florets, more or less covered with purple spots. Lateral spikelets: paleas more or less densely pilose, especially on the lower 1/2; anthers 1.2–1.8 mm; rachillas about 0.3 mm, yellow. 2n = 14.

Hordeum murinum subsp. glaucum grows in grasslands, fields, and waste places. It is native to the eastern Mediterranean area. It is now common in arid areas of the western United States, and is also known from scattered locations elsewhere in the Flora region.

Hordeum murinum subsp. leporinum (Link) Arcang.
Mouse Barley

Plants winter annuals. Culms 30–110 cm. Leaves green. Spikes green at anthesis, often more or less purple just before maturity. Central floret pedicellate; lemmas and awns shorter than those of the lateral florets; anthers 0.9–3 mm. Lateral spikelets: paleas scabrous on the lower 1/2; anthers 1.2–3.2 mm; rachillas about 0.25 mm, pale. 2n = 14, 28, 42.

Hordeum murinum subsp. leporinum grows in waste places, roadsides, and disturbed areas in arid regions. It is native to the Mediterranean region. It is now established in the Flora region, being most common in the western United States. A hexaploid cytotype has been found in Turkey, Armenia, Turkmenistan, and Iran. It has been named H. leporinum var. simulans Bowden. It is treated here as part of H. murinum subsp. leporinum.

Hordeum murinum L. subsp. murinum
Wall Barley, Farmer’s Foxtail, Way Barley

Plants winter annuals. Culms 30–60 cm. Leaves green. Spikes green. Central floret sessile to subsessile; lemmas subequal to those of the lateral florets, awns longer than those of the lateral florets; anthers 0.8–1.4 mm. Lateral spikelets: paleas almost glabrous; anthers 0.8–1.4 mm; rachillas about 0.15 mm, pale. 2n = 28.

Hordeum murinum subsp. murinum grows in waste places that are somewhat moist. It is native to Europe. Within the Flora region, it has the most restricted distribution of the three subspecies, being found from Washington to Arizona, and in scattered locations from Maine to Virginia.

 

10. Hordeum bulbosum L.
Bulbous Barley

Plants perennial. Culms to 135 cm, erect or somewhat geniculate; basal internodes usually bulbous, with 1–4 ellipsoid to pyriform bulbs per culm; nodes glabrous. Sheaths glabrous or pubescent; auricles well developed, to 5.5 mm; blades to 6 mm wide, flat, scabrous, often also pubescent. Spikes 4.5–16.5 cm. Central spikelets subsessile; glumes 10–25 mm, flattened near the base, margins more or less ciliate; lemmas glabrous, awns 12–50 mm; lodicules densely pilose; anthers 4.5–10 mm, yellow to violet. Lateral spikelets: lower glumes flattened near the base; upper glumes setaceous; lemmas usually unawned, sometimes awned, awns to 14 mm; anthers to 9 mm. 2n = 14, 28.

Hordeum bulbosum is native to the eastern Mediterranean and western Asia. In the Flora region, it is known as an occasional escape from breeding programs. In its native range it is found in a wide range of habitats, from wet meadows to dry hillsides, roadsides, and abandoned fields. It is one of two obligate outcrossers in the genus, H. brevisubulatum (Trin.) Link being the other.

 

11. Hordeum vulgare L.
Barley, Orge, Orge Vulgaire

Plants summer or winter annuals; loosely tufted. Culms to 100(150) cm, usually erect; nodes glabrous. Lower sheaths pilose; upper sheaths glabrous; auricles to 6 mm, well developed even on the upper leaves; blades to 30 cm long, 5–15 mm wide, flat, scabrous or glabrous. Spikes 5–10 cm long, 0.8–2 cm wide, green to purplish or blackish; nodes 10–30, with 3 spikelets per node, 0–2 lateral spikelets, in addition to the central spikelets, forming seed at maturity (resulting in 2-, 4-, and 6-rowed barley); rachises usually not disarticulating at maturity. Central spikelets sessile; glumes 10–30 mm, pubescent, flattened near the base; lemmas 6–12 mm long, 3+ mm wide, glabrous, sometimes scabrous, particularly distally, unawned or awned, awns 30–180 mm, usually scabrous; anthers 6–10 mm, yellowish. Lateral spikelets usually sessile if seed-forming, pedicellate if sterile; pedicels to 3 mm; lemmas usually 6–15 mm, awned when fertile, obtuse to acute when sterile. 2n = 14 (28).

Hordeum vulgare is native to Eurasia. Plants in the Flora region belong to the cultivated subspecies, H. vulgare L. subsp. vulgare. The progenitor of cultivated barley, H. vulgare subsp. spontaneum (K. Koch) Thell., has a brittle rachis, tough awn, and, often, shrunken seeds. It does not grow in the Flora region.

Hordeum vulgare subsp. vulgare was first domesticated in western Asia. It is now grown in most temperate parts of the world. In the Flora region, it occurs as a cultivated species that is often found as an adventive in fields, roadsides, and waste places throughout the region, not just at the locations shown on the map. There are many distinctive, but interfertile, forms. Bothmer et al. (1995) presented an artificial classification of such forms.