Arrhenatherum elatius

Tall Oatgrass

Field view of Arrhenatherum elatius, common name Tall Oatgrass.

Tall Oatgrass often shows as spike-like.

You can often see branches on the lower part of the seedhead, so it is not a spike.

The awns are only 3/8 inch long and are bent only once after drying. Spikelets have two florets but just one has an awn.

A micro view of singly-bent awns arising from the base of the lemma. The awns were straight until dried.

Roots of Tall Oatgrass, a perennial.

How to Identify Tall Oatgrass

  Tall Oatgrass is usually about hip to head high, seeding early in the year. It is distinguished by having two florets per spikelet but only one of these florets having an awn arising from the base of the lemma. The awn bends once after drying.

Similar Species

  There are many tall grasses with a spike-like panicle. Tall Oatgrass is different because each spikelet has two florets but only one is awned. This arrangement is sometimes seen in the "finger grasses" and especially in Little Bluestem (Schizachyrium scoparium). However, in all these look-alikes the single awn arises from the top of the lemma as in most grasses, rather than at the lemma base as in oat grasses.