An Illustrated Guide to ARIZONA WEEDS

The University of Arizona Press

WILD OAT, oatgrass, wheat oats, flaxgrass

Illustration

GRASS FAMILY-Gramineae

WILD OAT-Avena fatua L.

DESCRIPTION-Wild oat is a restricted noxious-weed in Arizona. It is a stout annual, 1 to 4 feet high, with a large root system, and reproduces by seed. The leaf blades, 3 to 8 inches long, and about 1/4 to 1/2 inch broad, are thin and rough. The flowering part is large and spreading. Each spikelet is about 1 inch long without the bristle, and has 2 to 4 flowering bracts. These bracts have reddish-brown hairs at the base and, arising from the center back of each is a dark, stout, 1 1/4 to 1 2/3 inch long bristle. The bristle is bent sharply near the center, and the lower part is twisted slightly. The white or yellowish to gray, brown, or black grain is silky, hairy, and about l/3 inch long.

DISTRIBUTION-Wild oat is one of the most troublesome winter crop pests in the state. It has been estimated that most small field grains in the Salt River Valley vary in content from 1 percent to 75 percent of wild oat. It is a common weed in disturbed soil and waste places throughout most of the state; up to 8,250 feet.

CULTIVATED OAT-Avena sativa L.

DESCRIPTION-Cultivated oat and its varieties closely resemble wild oat, but the bases of the flowering bracts are not hairy, and if a bristle is present, it is shorter and straight, not bent in the center.

Copyright (c) 1972 The Arizona Board of Regents



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