Bromus tectorum |
Bromus secalinus |
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cheatgrass, downy brome, downy chess |
rye brome |
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Habit | Plants annual, 5–90 cm tall. | Plants annual, 20–80(120)cm tall. |
Culms | puberulent. |
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Leaves | sheaths densely and softly retrorsely pubescent to pilose; upper sheaths sometimes glabrous; blades 1–16 cm × 1–6 mm, softly hairy on both surfaces. |
sheaths glabrous or loosely pubescent and becoming glabrous; blades 15–30 cm × 1–12 mm; lower surfaces pilose or glabrous; upper surfaces pilose. |
Inflorescences | 5–20 × 3–8 cm; open, nodding; branches 1–4 cm, drooping, 1-sided and longer than the spikelets, usually at least 1 branch with 4–8 spikelets. |
5–23 × 2.5–12 cm; open, nodding; branches spreading to ascending; lower branches slightly drooping; some pedicels longer than their spikelets. |
Spikelets | 10–20 mm, moderately laterally compressed, not densely crowded, 4–8 florets. |
10–20 mm; ovoid-lanceolate or ovate, laterally compressed, not purple-tinged, with 4–9(10) florets; floret bases visible at maturity; rachilla internodes visible at maturity. |
Glumes | villous, pubescent, or glabrous; lower glumes 4–9 mm, 1-veined; upper glumes 7–13 mm, 3–5-veined. |
scabrous or glabrous; lower glumes 4–6 mm, 3–5-veined; upper glumes 6–7 mm, 7-veined. |
Lemmas | 9–12 mm, lanceolate, glabrous or pubescent to pilose, 5–7-veined; tips acuminate; hyaline; bifid, with teeth 0.8–2(3)mm, awned; lemma awns 10–18 mm; straight. |
6.5– 8.5(10) × 1.7–2.5 mm, elliptic; leathery, rounded over the back; backs glabrous, sometimes pubescent, scabrous to puberulent on the margins and near the tips, obscurely 7-veined; veins usually not raised and thickened; margins smoothly curved, inrolled at maturity; tips acute to obtuse; bifid, with teeth less than 1 mm, awned; lemma awns (0)3–6(9.5)mm; straight or flexuous, arising less than 1.5 mm below the lemma tips. |
Anthers | 0.5–1 mm. |
1–3 mm. |
2n | =14. |
=14, 28. |
Bromus tectorum |
Bromus secalinus |
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Distribution | ||
Discussion | Disturbed areas, sagebrush steppe, degraded grasslands, roadsides. 0–2400 m. BR, BW, Casc, Col, CR, ECas, Lava, Owy, Sisk, WV. CA, ID, NV, WA; throughout North America; worldwide. Exotic. Bromus tectorum is a relatively short grass with drooping inflorescences. Similar B. sterilis and B. diandrus have longer glumes, lemmas, and awns, and spikelets that hang down at a shallower angle than those of B. tectorum. The introduction of B. tectorum to shrub steppe habitats during a time of massive overgrazing in the late 1800s has made restoration of native plant communities difficult or impossible, even where grazing no longer occurs. Fast-growing B. tectorum seedlings outcompete slower growing native grass seedlings for water in drying soils. At maturity, the awns make B. tectorum unpalatable to livestock. |
Disturbed areas, ditches, moist meadows, shorelines. 0–1500m. BW, CR, ECas, Est, Sisk, WV. CA, ID, NV, WA; throughout most of North America; Europe. Exotic. Mature B. secalinus is identified by the strongly inrolled lemmas enfolding the inrolled caryopses. The spreading florets expose the florets and rachilla joints. |
Source | Flora of Oregon, volume 1, page 374 Barbara Wilson, Richard Brainerd, Nick Otting |
Flora of Oregon, volume 1, page 373 Barbara Wilson, Richard Brainerd, Nick Otting |
Sibling taxa | ||
Synonyms | Bromus tectorum var. glabratus, Bromus tectorum var. nudus, Bromus tectorum var. tectorum | Bromus secalinus var. secalinus, Bromus secalinus var. velutinus |
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