Avena fatua
Wild Oats
Field view of dry Avena fatua, common name Wild Oats. |
Wild Oats in fruit, still green and growing its seeds. |
This shows the shape and the relatively large size of the Wild Oats spikelets, some with seeds inside. |
Growth pattern of Wild Oats at root level. |
Two of the characteristic open panicles of Avena fatua. |
Avena fatua glumes are about 3/4 of an inch long. You can see the florets inside some of them. |
Each spikelet has its large whitish glumes (here more of a tan) wrapping around the dark-colored florets inside. These florets are the seed structures (with seed inside). |
The spikelet is the basic unit of grass inflorescence. It consists (usually) of two glumes (above) and in Avena fatua there are one to three dark florets (below). |
These florets are separated so you can see that they are very hairy. Their single awn is bent and, rather unusually, arises from the side instead of the tip of the floret. |
How to Identify Wild Oats
The large white glumes of Avena fatua are persistent after the seeds (florets) fall out. In fact, the florets usually hang down under the glumes, allowing them to drop easily. These glumes make the plant easy to recognize even after seed dispersal. A happy plant will grow about waist to shoulder high.
Similar Species
As I started studying grasses, I confused Wild Oats with Achnatherum hymenoides (Indian Ricegrass, silly me) when I saw them in seed as I drove by. Each grows beside roads. The Indian Ricegrass plant is similar in size to Wild Oats. Both plants have persistent white glumes, but the glumes of Indian Ricegrass are much smaller and of different shape than those of Wild Oats.