Compare California Oats (Avena)
by Bruce Homer-Smith

There are four species of oats in California. Here are things to look for when deciding which one you’re looking at.

Cultivated Oats (Avena sativa) is the domesticated oat grown worldwide for food. It generally has no awns and no hairs at the base of the florets, as the other oats do. This is useful for harvesting. Some wild versions have reverted a bit, but they still have shorter awns (1/2”) than the others.

Cultivated Oats (Avena sativa) – photo by Keir Morse

Sterile Oats (Avena sterilis) is primarily found around San Diego and has bigger parts than the other oats. Its leaves are longer, growing to two feet. Its spikelets tend to be larger, growing to 2”. Awns are longer, growing to 3.5” long.

Sterile Oats (Avena sterilis) – photo by Keir Morse

The remaining two oats, Wild Oats and Slender Oats are trickier to tell apart. They both have lots of hair inside the glumes at the base of the floret. They both have awns that bend when mature, growing to 1.5” long. They’re both widespread, invasive weeds. But Wild Oats tends to be bigger, as you’ll see below.

Wild Oats (Avena fatua) has somewhat wider florets, grows to 5 feet tall, and often has leaves longer than 1 foot.

Wild Oats (Avena fatua) – photo by Wilde Legard

Slender Oats (Avena barbata) has more slender florets, grows to only 3 feet tall, and has leaves less than 1 foot.

Slender Oats (Avena barbata) – photo by Keir Morse

Corrections/Comments: bruce@PlantID.net