OregonFlora: Bromus tectorum vs. Bromus briziformis

	Bromus tectorum	Bromus briziformis
	cheatgrass, downy brome, downy chess	rattlesnake brome
Habit	Plants annual, 5–90 cm tall.	Plants annual, 20–65 cm tall.
Culms	puberulent.
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 densely pilose; blades 3–13 cm × 2–4 mm, pilose to pubescent on both surfaces.
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.	5–15 × 3–7 cm; open, nodding; pedicels sometimes longer than the spikelets, curved to reflexed.
Spikelets	10–20 mm, moderately laterally compressed, not densely crowded, 4–8 florets.	15–30 × 8–12 mm; ovate, laterally compressed, usually dangling, with 9–15 florets; floret bases usually concealed at maturity; rachilla internodes concealed at maturity.
Glumes	villous, pubescent, or glabrous; lower glumes 4–9 mm, 1-veined; upper glumes 7–13 mm, 3–5-veined.	smooth or minutely scabrous; lower glumes 5–6 mm, 3–5-veined; upper glumes 6–8 mm, 7–9-veined.
Caryopses		about as long as the paleas.
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.	9–10 mm long, 6–8 mm wide, inflated, obovate or rhombic; leathery; smooth or scabridulous, obscurely 9-veined; veins usually not raised and thickened; margins hyaline, 1–1.3 mm wide, abruptly angled, not inrolled at maturity; tips acute to obtuse; bifid; teeth shorter than 1 mm, usually awnless; lemma awns; if present; to 1 mm, arising less than 1.5 mm below the lemma tips.
Anthers	0.5–1 mm.	0.7–1 mm.
2n	=14.	=14.

	Bromus tectorum	Bromus briziformis
Distribution	[WildflowerSearch map] [BONAP county map]	[WildflowerSearch map] [BONAP county map]
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 places, roadsides, forest openings, sand dunes, overgrazed rangeland. 0–1800 m. BR, BW, Col, ECas, Lava, WV. CA, ID, NV, WA; throughout North America; southwestern Asia, Europe. Exotic. Unusual inflated florets make Bromus briziformis unique among Oregon bromes, but it can be confused with Briza maxima. In the latter species, the florets spread more widely, so that the angle between the glumes is almost 180°. Records of B. briziformis west of the Cascades have often been misidentified B. maxima. The dry, mature inflorescences of this species look somewhat like the tails of rattlesnakes and also make a disturbing rattling sound as one walks through a population of ripe plants.
Source	Flora of Oregon, volume 1, page 374 Barbara Wilson, Richard Brainerd, Nick Otting	Flora of Oregon, volume 1, page 368 Barbara Wilson, Richard Brainerd, Nick Otting
Sibling taxa	B. arenarius, B. briziformis, B. catharticus, B. ciliatus, B. commutatus, B. diandrus, B. hordeaceus, B. inermis, B. japonicus, B. laevipes, B. madritensis, B. orcuttianus, B. pacificus, B. rubens, B. secalinus, B. sitchensis, B. squarrosus, B. sterilis, B. suksdorfii, B. vulgaris	B. arenarius, B. catharticus, B. ciliatus, B. commutatus, B. diandrus, B. hordeaceus, B. inermis, B. japonicus, B. laevipes, B. madritensis, B. orcuttianus, B. pacificus, B. rubens, B. secalinus, B. sitchensis, B. squarrosus, B. sterilis, B. suksdorfii, B. tectorum, B. vulgaris
Synonyms	Bromus tectorum var. glabratus, Bromus tectorum var. nudus, Bromus tectorum var. tectorum
Web links	Local floras: BC, CA, OR, WA Local Web sites: CalFlora, CalPhotos, Flora NW, PNW Herbaria WildflowerSearch iNaturalist (observations) USDA Plants Database LBJ Wildflower Center SEINet Plants of the World Online Encyclopedia of Life Wikipedia Google Image Search	Local floras: BC, CA, OR, WA Local Web sites: CalFlora, CalPhotos, Flora NW, PNW Herbaria WildflowerSearch iNaturalist (observations) USDA Plants Database LBJ Wildflower Center SEINet Plants of the World Online Encyclopedia of Life Wikipedia Google Image Search

Bromus briziformis

cheatgrass, downy brome, downy chess

rattlesnake brome

Habit

Plants annual, 5–90 cm tall.

Plants annual, 20–65 cm tall.

Culms

puberulent.

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 densely pilose;

blades 3–13 cm × 2–4 mm, pilose to pubescent on both surfaces.

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.

5–15 × 3–7 cm; open, nodding;

pedicels sometimes longer than the spikelets, curved to reflexed.

Spikelets

10–20 mm, moderately laterally compressed, not densely crowded, 4–8 florets.

15–30 × 8–12 mm; ovate, laterally compressed, usually dangling, with 9–15 florets;

floret bases usually concealed at maturity;

rachilla internodes concealed at maturity.

Glumes

villous, pubescent, or glabrous;

lower glumes 4–9 mm, 1-veined;

upper glumes 7–13 mm, 3–5-veined.

smooth or minutely scabrous;

lower glumes 5–6 mm, 3–5-veined;

upper glumes 6–8 mm, 7–9-veined.

Caryopses

about as long as the paleas.

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.

9–10 mm long, 6–8 mm wide, inflated, obovate or rhombic; leathery; smooth or scabridulous, obscurely 9-veined;

veins usually not raised and thickened;

margins hyaline, 1–1.3 mm wide, abruptly angled, not inrolled at maturity;

tips acute to obtuse; bifid;

teeth shorter than 1 mm, usually awnless;

lemma awns; if present; to 1 mm, arising less than 1.5 mm below the lemma tips.

Anthers

0.5–1 mm.

0.7–1 mm.

=14.

Bromus briziformis

Distribution

[WildflowerSearch map]

[BONAP county map]

[WildflowerSearch map]

[BONAP county map]

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 places, roadsides, forest openings, sand dunes, overgrazed rangeland. 0–1800 m. BR, BW, Col, ECas, Lava, WV. CA, ID, NV, WA; throughout North America; southwestern Asia, Europe. Exotic.

Unusual inflated florets make Bromus briziformis unique among Oregon bromes, but it can be confused with Briza maxima. In the latter species, the florets spread more widely, so that the angle between the glumes is almost 180°. Records of B. briziformis west of the Cascades have often been misidentified B. maxima. The dry, mature inflorescences of this species look somewhat like the tails of rattlesnakes and also make a disturbing rattling sound as one walks through a population of ripe plants.

Source

Flora of Oregon, volume 1, page 374
Barbara Wilson, Richard Brainerd, Nick Otting

Flora of Oregon, volume 1, page 368
Barbara Wilson, Richard Brainerd, Nick Otting

Sibling taxa