Plants annual. Culms 30-120 cm, initially prostrate, becoming
erect at maturity. Sheaths glabrous or hairy; ligules 3-8
mm, acute to truncate-mucronate; blades 8-60 cm long, 4-18 mm wide,
scabridulous, often ciliolate on the margins. Panicles 10-45 cm
long, 5-25 cm wide. Spikelets 24-50 mm, with 2-5 florets; disarticulation beneath
the basal floret, the florets falling as a unit; disarticulation scar oval
to round-elliptic. Glumes subequal, 20-50 mm, 9-11-veined; calluses bearded,
hairs to 1/5 the length of the lemmas; lemmas 17-40 mm, usually
densely strigose below midlength, varying to sparsely strigose, glabrous,
or scabridulous, apices bidentate to bisubulate, teeth 1-1.5 mm, awns 30-90
mm, arising in the middle 1/3; lodicules without a lobe on the wing; anthers 2.5-4
mm. 2n = 42.
Avena sterilis is native from the Mediterranean region to Afghanistan; it now grows on all continents. It has become naturalized in California and Oregon, where it can be found in fields, vineyards, orchards, and on hillsides. It is listed as a noxious weed by the U. S. Department of Agriculture.
