Bromus arizonicus |
Bromus catharticus |
|||||
---|---|---|---|---|---|---|
Arizona brome |
rescue brome, rescue grass, rescuegras |
|||||
Habit | Plants annual; tufted. | Plants annual, biennial, or perennial; loosely cespitose or tufted. | ||||
Culms | 30-90 cm tall, to 3 mm thick, erect. |
30-120 cm tall, 2-4 mm thick, erect or decumbent. |
||||
Sheaths | retrorsely pilose, sometimes mostly glabrous, throats sometimes with hairs; auricles absent; ligules 1-4 mm, usually glabrous, obtuse, erose; blades 8-18 cm long, 3-9 mm wide, flat, sparsely pilose on both surfaces or the abaxial surfaces glabrous. |
usually densely, often retrorsely, hairy, hairs sometimes confined to the throat; auricles absent; ligules 1-4 mm, glabrous or pilose, obtuse, lacerate to erose; blades 4-30 cm long, 3-10 mm wide, flat, glabrous or hairy on both surfaces. |
||||
Panicles | 12-25 cm, somewhat contracted or open; lower branches shorter than 10 cm, 2-3(5) per node, initially erect to ascending, spreading at maturity, with 1-2 spikelets variously distributed. |
9-28 cm, usually open, erect or nodding; lower branches shorter than 10 cm, 1-4 per node, spreading or ascending, with up to 5 spikelets variously distributed. |
||||
Spikelets | 18-25 mm, elliptic to lanceolate, strongly laterally compressed, with 4-8 florets. |
(17)20-40 mm, shorter than at least some pedicels and branches, elliptic to lanceolate, strongly laterally compressed, not crowded or overlapping, with 4-12 florets. |
||||
Glumes | subequal, smooth or scabrous; lower glumes 8-12.5 mm, 3-veined; upper glumes 9.5-14 mm, 7-veined, about as long as the lowest lemma; lemmas 9.5-14 mm, lanceolate, laterally compressed, prominently 7-veined, strongly keeled at least distally, glabrous or pubescent distally or throughout, marginal hairs, if present, longer than those elsewhere, apices entire or with acute teeth shorter than 1 mm; awns 6-13 mm, sometimes slightly geniculate; anthers 0.4-0.5 mm. |
smooth or scabrous, glabrous or pubescent; lower glumes 7-12 mm, 5-7(9)-veined; upper glumes 9-17 mm, 7-9(11)-veined, shorter than the lowest lemma; lemmas 11-20 mm, lanceolate, laterally compressed, strongly keeled, usually glabrous, sometimes pubescent distally, smooth or scabrous, 9-13-veined, veins often raised and riblike, margins sometimes conspicuous, hyaline, whitish or partly purplish, apices entire or toothed, teeth acute, shorter than 1 mm; awns absent or to 10 mm; anthers 0.5-1 mm in cleistogamous florets, 2-5 mm in chasmogamous florets. |
||||
2n | = 84. |
= 42. |
||||
Bromus arizonicus |
Bromus catharticus |
|||||
Distribution |
AZ; CA; NV; TX
|
AL; AR; AZ; CA; CO; DC; FL; GA; IA; IL; KS; KY; LA; MD; MO; MS; NC; ND; NE; NJ; NM; NV; NY; OH; OK; OR; PA; SC; SD; TN; TX; UT; VA; HI; AB; NF; ON
|
||||
Discussion | Bromus arizonicus grows in dry, open areas and disturbed ground of the southwest, usually below 2000 m. Its range extends from California and southern Nevada into Arizona, New Mexico, and northern Mexico. Stebbins et al. (1944) demonstrated that, like Bromus carinatus var. carinatus, B. arizonicus obtained three of its genomes from B. catharticus or a close relative, but the remaining three genomes are not homologous with those in B. carinatus, probably being derived from a species in a section other than Ceratochloa. The small anthers of B. arizonicus strongly suggest that most seed is produced by selfing. (Discussion copyrighted by Flora of North America; reprinted with permission.) |
|||||
Key |
|
|||||
Source | FNA vol. 24, p. 201. | FNA vol. 24, p. 199. | ||||
Parent taxa | Poaceae > subfam. Pooideae > tribe Bromeae > Bromus > sect. Ceratochloa | Poaceae > subfam. Pooideae > tribe Bromeae > Bromus > sect. Ceratochloa | ||||
Sibling taxa | ||||||
Subordinate taxa | ||||||
Synonyms | B. berteroanus var. excelsus | Ceratochloa unioloides, B. willdenowii, B. unioloides | ||||
Name authority | (Shear) Stebbins | Vahl | ||||
Web links |
|