Wild oat  (Avena fatua)

Wild oat is an erect, cool season annual grass with open-branched, nodding flower clusters. It is found throughout California, except for the Sonoran Desert (low desert), up to 3900 feet (1200 m) and has been well established here since the late 1700s. Its expansion in its new range has given rise to many genetically distinct ecotypes. Wild oat inhabits agricultural lands and other disturbed areas. It makes good forage for livestock.

Habitat

Grassland, crop fields, orchards, vineyards, gardens, roadsides, and other disturbed sites.

Seedling

Seedlings have hairy leaves, like hare barley, Hordeum murinum ssp. leporinum. However, in wild oat, the seed clings to the seedling from which it is growing for a long time.

Mature plant

The sturdy, mature plant grows to about 4 feet (1.2 m) tall. Stems are round in cross-section, hairless, or nearly so. Leaves are flat, rolled in the bud, and up to 8 inches (20 cm) in length. Leaves often twist counter-clockwise. Usually a few soft hairs grow from the edge of the base of the blade. The leaf sheath is open and usually has a hairless edge. Roots are fibrous and typically extensive.

Collar region

Wild oat has a tall, membranous ligule with a rounded, jagged top. There are no auricles.

Flowers

Wild oats are in bloom mostly from March through June. The flower head is open and branched. Spikelets hang like pendants from the flowering branches.

Reproduction

Reproduces by seed.

Related or similar plants

• Ripgut brome, Bromus diandrus, seedling
• Hare barley, Hordeum murinum ssp. leporinum

More information

• Grass ID illustration
• Calflora's distribution map
• For agriculture: UC IPM Pest Management Guidelines