Origin:
Native to Europe, now widespread in the United States, being most common in the western half of the country. In California it is the most widespread and noxious of the winter annual grass weeds.
Biology:
A winter annual that grows and is a problem in all crop and non-crop situations. In pastures it is an excellent forage grass. Seeds germinate from late fall throughout the winter and into early spring, and plants mature until late spring or early summer. The awns tend to twist and wind as they absorb or lose moisture, causing them to force themselves into the soil.
Identification:
Mature plants may reach over 4 feet tall, with several stems arising from the base. Stems are stiff and up to ¼ inch wide. Leaves are thin, rough, and up to 12 inches long and ½ inch wide. The sheath at the leaf base is smooth and almost hairless. The flower heads are open and spreading, and may be 16 inches long. Each flower group, or spikelet, is about 1 inch long, and awns are present that are up to 1.6 inches long. Similar to Slender Oat, which has flower groups of only 2 seeds and very short awns, and to Sterile Oat, which differs by having flower spikelets up to 1.5 inches long and awns up to 2.5 inches long.
Characteristicts Important to Control:
Cool, moist conditions encourage seed germination.
