Rye Grasses

General characteristics of ryes

Likely you know rye grass when you see it but knowing exactly which of the species found in Illinois can be challenging. Understanding the characteristics of a genus, or closely related group of plants, is a great first place to start when telling grasses apart. Let’s look at the rye grasses in the Elymus genus. These four are found in every county in the Illinois.

Since they are in the same genus, there are general identification characteristics that apply to the ryes. They are cool-season grasses, so they will start to green up in spring, flowering in early to mid-summer. They will retain their seed heads into winter or even the next growing season.

They all have auricles, which are small, arm-like extensions of leafy material in the collar region. Auricles arise from the base of the leaf blade and wrap around the stem. These grasses also have a white membranous ligule. The leaves are in general pretty non-descript, but they are about 1/2 to 2/3 inch across, usually pretty shiny, and oftentimes they curve in the collar region so their undersides face up.

If we look at the inflorescences of these grasses, they have spikes with awned spikelets (not all ryes have awns, but the ones we'll look at today do). The way the spike is held (erect or drooping) and the length and direction of the spikelets and awns can be used to help distinguish them, but the flower can be the distinguishing factor.

auricles of rye grasses
Auricles look like little arms that extend from the base of leaf blade and wrap around the grass stem.
rye grasses have spike inflorescences with awns
Rye grasses have spike inflorescences with awns.

Bottlebrush Grass

Bottlebrush Grass's, Elymus hystrix, common name accurately describes the appearance of the plant. This grass has dark green, hairless, rather floppy leaves. It grows between 3 and 5 feet tall. You typically find it in the woods or on a woodland edge.

The inflorescence of bottlebrush grass is a spike, 3-8 inches long, which can either be held erect or droop. The spikelets each have a pair of awns that are 1-2 inches in length. The spikelets are held 90 degrees away from the rachis and are spread out along the rachis. Altogether, this leads the inflorescence to resemble a bottlebrush.

inflorescence of bottlebrush grass
Bottlebrush Grass has a spike inflorescence with spikelets spaced apart and held 90 degrees away from the stem.
paired spikelets of bottlebrush grass
Spikelets of Bottlebrush Grass are paired and have long awns.

Virginia Wild Rye

Virginia Wild Rye, Elymus virginicus, is found in a range of habitats, from the woods to prairies. It has weak, shiny, hairless leaves and grows between 2 and 4 feet tall.

The inflorescence of this grass is a spike, 2 to 6 inches long, which is typically held erect, but can droop sometimes. The spikelets are densely clustered along the rachis. The awns are shorter in this grass than Bottlebrush Grass, typically not more than an inch. Both spikelets and awns are held up towards the top of the inflorescence. The inflorescence typically emerges right above a leaf, so the bottom of the spike is inside the sheath.

spikes of Virginia wild rye
Virginia Wild Rye has spikes that stay upright and short awns.
senesced spikes of Virginia Wild Rye
Virginia Wild Rye looks dried out in the summer since it is a cool-season grass.

Silky Wild Rye

Elymus villosus, Silky Wild Rye, can be found in woods and woodland edges. It’s 2 to 3 feet tall. The leaves of this rye can be slightly hairy, and the leaf sheaths are covered in white hairs that are spreading, meaning they are held out from the stem, rather than hug it.

The inflorescence of this species will nod, or droop to the side. It’s a bit smaller in size than some of the other ryes, only 3 to 4 inches long. The spikelets are densely clustered in the spike and point up. The awns of this grass spread outwards slightly.

spike of silky wild rye
Silky Wild Rye has a nodding spike inflorescence with hairy, awned spikelets.
hairy leaf sheaths of silky wild rye
The leaf sheaths of Silky Wild Rye are covered in soft, silky hairs.

Canada Wild Rye

Canada Wild Rye, Elymus canadensis, despite the name, is a native grass to Illinois. This one prefers some sun, so you’ll find it in prairies and woodland edges, but not typically in dense woods. It will grow between 3 to 5 feet tall.

The spike inflorescence of this grass grows between 5 and 9 inches long, and it droops strongly. The spikelets of this grass are held up towards the top of the inflorescence. The awns, 3/4 to 1 1/2 inches in length, will curve strongly backwards as the grass matures. This produces a very distinctive inflorescence that can be picked out from quite a distance.

inflorescence of Canada Wild Rye
Canada Wild Rye's spike inflorescence droops and the awns start to curl backwards.
senesced inflorescence of Canada Wild Rye
Canada Wild Rye once fully senesced, with awns curved backwards.