GRASSES OF THE COLUMBIA BASIN OF BRITISH COLUMBIA
Heather Stewart, Richard Hebda
Major Groups of Grasses
Table of Contents
Glossary

Agropyron

Wheatgrasses

The name Agropyron comes from the Greek word for wild wheat, and Agropyron species have a wheatlike appearance. There has been some controversy concerning the species included in this genus. Hitchcock et al. (1969) recognized nine species of Agropyron. Today there is general agreement that Agropyron should be restricted to the "crested wheatgrasses". These species are perennial plants with a stem axis that does not come apart at maturity, a flowerhead that is a spike, spikelets that diverge from the stem axis at an angle of 30° or more and one spikelet at each node. The species that were traditionally contained within Agropyron are now treated in Elymus, Thinopyrum, Pascopyrum and Pseudoroegneria. There are three B.C. species remaining in the genus Agropyron, and these are: Crested Wheatgrass, Desert Wheatgrass and Siberian Wheatgrass. In the Columbia Basin region only Crested Wheatgrass and Siberian Wheatgrass have been collected.

Agropyron- Adapted from Douglas et al. (1994)
1a. Spikelet spreading from the stem axis 30 or more; the
distance between the spikelets is less than 1 mm............................Agropyron cristatum
1b. Spikelet is pressed to the stem axis < 30; the distance
between the spikelets is greater than 1mm ..........................................Agropyron fragile

 

Agropyron cristatum (L.) Gaertn. ssp. pectinatum (Bieb.) Tzvelev

Crested Wheatgrass

Plant: Agropyron cristatum is an introduced species that grows to 50-100 cm tall. It is a tufted perennial with densely fibrous roots, but no rhizome. The flowerhead is composed of a flattened spike containing spikelets that resemble the teeth in a comb -- thus the subspecies name pectinatum which is from pectinate, meaning comblike.

Leaves and Stem: The lower leaf sheaths are most often hairless, but may be occasionally soft-hairy. The slender, clawlike auricles are 1 mm long, and the hairy ligules are <1 mm long. Flat leaf blades are 2-5 mm wide, and are usually hairy on the upper surface.

Flowerhead and Flowers: The spikes are 2-6 cm long, and have spikelets that diverge from the hairy stem axis like the teeth of a comb. The spikelets overlap and spread out rather than press close to the axis. The longest glume is about the length of the first flower and the other glume is shorter. The awns of the glumes and the lemmas are 2-4 mm long, and the awns of the lemmas are slightly bent.

Habitat: Crested Wheatgrass was introduced from Russia for forage purposes and has been extensively used to revegetate rangeland. It occurs along roadsides, in fields and disturbed sites. In the Columbia Basin it grows in sites from Tobacco Plains at the U.S./Canada border, to as far north as Revelstoke.

Similar Species: In British Columbia, the three species in the genus Agropyron hybridize, so it is often difficult to tell them apart. In the Columbia Basin, Desert Wheatgrass has not yet been collected. Douglas et al. (1994) distinguish Crested Wheatgrass on the basis of the spreading angle of the spikelet from the stem axis. Greater than 30° indicates Agropyron cristatum ssp. pectinatum.

Agropyron fragile (Roth) P. Candargy
Agropyron sibiricum (Wild.) Beauv.

Siberian Wheatgrass

Plant: Agropyron fragile is an introduced species that grows to 70 cm tall. This perennial is tufted. The flowerhead is a comblike spike that has shorter "teeth" and therefore appears less comblike than A. cristatum ssp. pectinatum.

Leaves and Stem: The lower leaf sheaths are most often hairless but may be occasionally soft-hairy. The scarcely visible ligules are < 0.5 mm high consisting of a zone of hairs. The flat leaves are 4-5 mm wide.

Flowerhead and Flowers: The spike flowerhead is 3-7 cm long. Spikelets diverge from the stem axis at less than 30°. This arrangement gives the spikelets the appearance of being pressed tightly to the stem axis. The glumes are 4-5 mm long, with 1.5-mm-long awns. The lemmas are awnless or short-awned. The first glume is slightly longer than the second and about equal to the first flower.

Habitat: Siberian Wheatgrass was introduced from south central Russia and grows along roadsides, fields and wasteplaces. It occurs only at Wardner in the Columbia Basin.

Similar Species: Siberian Wheatgrass has awnless lemmas; however, this species interbreeds and hybridizes with Crested Wheatgrass, so it may be difficult to distinguish between these two species. The flowerhead of Crested Wheatgrass has longer spikelets and therefore appears more comblike than Siberian Wheatgrass. Crested Wheatgrass has a wider spike than Siberian Wheatgrass: 8-10 mm, compared to 5-6 mm.

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