Avena occidentalis

Durieu
Common names: Western oats
Treatment appears in FNA Volume 24. Treatment on page 737.
Please click on the illustration for a higher resolution version.
Illustrator: Cindy Roché

Copyright: Utah State University

Plants annual. Culms 50-80 cm, erect. Sheaths glabrous or sparsely pubescent, hairs 0.5-1 mm, sometimes confined to the margins; ligules of the lower leaves 3-5 mm, those of the upper leaves 1.5-2.5 mm, acute; blades 12-25 cm long, 5-11 mm wide. Panicles 15-26 cm. Spikelets 30-40 mm, with 3-4 (5) florets; disarticulation beneath each floret; disarticulation scars of the lower florets in a spikelet round to elliptic, those of the third and fourth florets heart-shaped. Glumes subequal, 28-40 mm, 7-9-veined; calluses bearded, hairs 3-5 mm; lemmas 14-26 mm, usually densely strigose below midlength, sometimes sparsely strigose or glabrous, veins not extending beyond the apices, apices bifid, teeth sometimes shortly aristate, awns arising at midlength; lodicules without lobes on the wing; anthers 2-3.2 mm. 2n = 42.

Discussion

Avena occidentalis is native to the Canary Islands, coastal North Africa, and Saudi Arabia; it is now established in western North America, from California to northern Mexico. It is often confused with A. fatua, but differs in its longer, narrower spikelets, greater number of florets, and the heart-shaped disarticulation scars of the distal florets.

Selected References

None.

Lower Taxa

None.

"decumbent" is not a number.

... more about "Avena occidentalis"
membranous +  and scarious +
0.2 cm2 mm <br />0.002 m <br /> (0.32 cm3.2 mm <br />0.0032 m <br />) +
Bernard R. Baum +
Durieu +
1 (?) +  and 3 (?) +
straight +
once-geniculate +
keeled +  and rounded +
pseudopetiolate +  and branching +
intravaginal +, extravaginal +, branching +  and basal +
swelling +
12 cm120 mm <br />0.12 m <br /> (25 cm250 mm <br />0.25 m <br />) +
not evident +
cross +, linear +  and narrowly lanceolate +
5mm;11mm +
spikelike +
rounded +  and pointed +
Western oats +
not branching +
50 cm500 mm <br />0.5 m <br /> (80 cm800 mm <br />0.8 m <br />) +
not woody +
1/4 +  and 1/3 +
liquid +, soft +  and hard +
capillary +
pistillate +  and staminate +
sometimes longer +
3 +  and 4 +
sterile +  and bisexual +
compressed +
reduced +
shorter or longer +
subtending +
subequal +
2.8 cm28 mm <br />0.028 m <br /> (4 cm40 mm <br />0.04 m <br />) +
membranous +
uncinate +
0.3 cm3 mm <br />0.003 m <br /> (0.5 cm5 mm <br />0.005 m <br />) +
0.15 cm1.5 mm <br />0.0015 m <br /> (0.25 cm2.5 mm <br />0.0025 m <br />) +
glabrous +  and strigose +
lanceolate +  and ovate +
1.4 cm14 mm <br />0.014 m <br /> (2.6 cm26 mm <br />0.026 m <br />) +
membranous +
inconspicuous +
not toothed +  and toothed +
concealed +  and prominent +
2 +  and 1 +
entire +  and bifid +
well-developed +
2-keeled +
spikelike +
15 cm150 mm <br />0.15 m <br /> (26 cm260 mm <br />0.26 m <br />) +
dry +  and fleshy +
not disarticulating +
not prolonged +
heart--shaped +
pubescent +  and glabrous +
15 +  and 50 +
round +  and elliptic +
3 cm30 mm <br />0.03 m <br /> (4 cm40 mm <br />0.04 m <br />) +
1 (?) +  and 3 (?) +
simple +  and compound +
2 (?) +  and 3 (?) +
Gramineae +
Avena occidentalis +
species +
membranous +
aristate +
parallel +  and converging +
stoloniferous +  and rhizomatous +
aquatic +  and terrestrial +