Elymus

By Bruce Homer-Smith

Elymus is a genus of grasses that includes Wheat Grass, Wild Rye, Squirreltail and Medusa Head. It’s in the Wheat Tribe.

· They have a spike inflorescence, with spikelets attaching directly to the stem. (Giant Wild Rye is an exception).

· Spikelets are laterally compressed (flattened rather than cylindrical).

· Spikelets often form in 2 ranks, creating a flattish inflorescence.

· Spikelets have two or more florets that are often awned. They generally stick out a bit beyond the glumes.

· Two of the longest-awned plants in California are Elymus – Medusa Head and Big Squirrel Tail. They have awns on the florets and the glumes.

Here are some examples:

Spikelets form a woven pattern along the stem.

Slender Wheatgrass

Elymus trachycaulus ssp. trachycaulus

Photo by Wilde Legard

Spikelets are 2-ranked and pressed into the stem. Beardless Wild Rye (Elymus triticoides)

Photo by Wilde Legard

These have really long awns.

Big Squirrel Tail Grass (Elymus multisetus)

Photo by Wilde Legard

Medusa Head (Elymus caput-medusae)

Photo by Wilde Legard

Elyo is the Greek word for “rolled up”. It refers to the grain being tightly embraced by the lemma and palea.

California has 40 species of Elymus. 39 of them are perennial, expanding each year either as bunch grasses or through rhizomes. The only exception is the annual, non-native Medusa Head.

Corrections/Comments: bruce@PlantID.net