Bromus arizonicus

(Shear) Stebbins
Common names: Arizona brome
Synonyms: Bromus berteroanus var. excelsus
Treatment appears in FNA Volume 24. Treatment on page 201.
Please click on the illustration for a higher resolution version.
Illustrator: Cindy Roché

Copyright: Utah State University

Plants annual; tufted. Culms 30-90 cm tall, to 3 mm thick, erect. 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. 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. Spikelets 18-25 mm, elliptic to lanceolate, strongly laterally compressed, with 4-8 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. 2n = 84.

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.

Selected References

None.

Lower Taxa

None.

"decumbent" is not a number.

... more about "Bromus arizonicus"
membranous +  and scarious +
0.04 cm0.4 mm <br />4.0e-4 m <br /> (0.05 cm0.5 mm <br />5.0e-4 m <br />) +
with acute teeth +  and entire +
Leon E. Pavlickf +
(Shear) Stebbins +
divaricate +
1 (?) +  and 3 (?) +
straight +
distinct +
subterminal +  and terminal +
geniculate +
0.6 cm6 mm <br />0.006 m <br /> (1.3 cm13 mm <br />0.013 m <br />) +
keeled +  and rounded +
pseudopetiolate +  and branching +
intravaginal +, extravaginal +, branching +  and basal +
swelling +
8 cm80 mm <br />0.08 m <br /> (18 cm180 mm <br />0.18 m <br />) +
not evident +
cross +, linear +  and narrowly lanceolate +
3mm;9mm +
drooping;reflexed;usually ascending;spreading +
spikelike +
Arizona brome +
not branching +
30 cm300 mm <br />0.3 m <br /> (90 cm900 mm <br />0.9 m <br />) +
5 cm50 mm <br />0.05 m <br /> (190 cm1,900 mm <br />1.9 m <br />) +
not woody +
0 cm0 mm <br />0 m <br /> (0.3 cm3 mm <br />0.003 m <br />) +
Calif. +, Ariz. +, Tex. +  and Nev. +
liquid +, soft +  and hard +
capillary +
pistillate +  and staminate +
sometimes longer +
4 +  and 8 +
terete +  and laterally compressed +
1-9(11)-veined +
always shorter +  and usually shorter +
lanceolate +
subtending +
pubescent +  and glabrous +
mucronate +  and acute +
subequal +
uncinate +
solid +  and hollow +
pubescent +  and glabrous +
keeled +, compressed +  and lanceolate +
0.95 cm9.5 mm <br />0.0095 m <br /> (1.4 cm14 mm <br />0.014 m <br />) +
herbaceous +  and coriaceous +
0.1 cm1 mm <br />0.001 m <br /> (0.4 cm4 mm <br />0.004 m <br />) +
membranous +
inconspicuous +
lanceolate +
fleshy +  and membranous +
spreading +, initially erect +  and ascending +
10 cm100 mm <br />0.1 m <br /> (?) +
0.8 cm8 mm <br />0.008 m <br /> (1.25 cm12.5 mm <br />0.0125 m <br />) +
1 cm10 mm <br />0.01 m <br /> (?) +
concealed +  and prominent +
2 +  and 1 +
hairy +  and glabrous +
well-developed +
reduced +
12 cm120 mm <br />0.12 m <br /> (25 cm250 mm <br />0.25 m <br />) +
dry +  and fleshy +
glabrous +  and pilose +
not viviparous +
compressed +, elliptic +  and lanceolate +
1.8 cm18 mm <br />0.018 m <br /> (2.5 cm25 mm <br />0.025 m <br />) +
1 (?) +  and 3 (?) +
simple +  and compound +
2 (?) +  and 3 (?) +
Bromus berteroanus var. excelsus +
Bromus arizonicus +
Bromus sect. Ceratochloa +
species +
membranous +
1 cm10 mm <br />0.01 m <br /> (?) +
0.95 cm9.5 mm <br />0.0095 m <br /> (1.4 cm14 mm <br />0.014 m <br />) +
aquatic +  and terrestrial +