Columbia Basin    Human History projects    Natural History Projects Thompson-Okanagan Upper Fraser Basin Peace River Northen Rockies Northwest

GRASSES OF THE COLUMBIA BASIN OF BRITISH COLUMBIA Heather Stewart, Richard Hebda Major Groups of Grasses Table of Contents Glossary Trisetum Trisetum are fairly palatable grasses, but they are not abundant as forage. In the alpine zone Trisetum spicatum is an important forage for deer and goats. Trisetum is from Greek words treis, meaning three, and seta meaning bristles, referring to the three awns on the type specimen for the genus. Trisetum Adapted from Douglas et al. 1994 1a. Lemmas awnless or with awns that rarely exceed 1 mm.................................Trisetum wolfii 1b. Lemmas awned; awns exceed the length of the lemmas.........................................................2 2a. Flowerhead is spikelike, dense; basal leaf sheaths are hairy and upper glume is not much longer than the lower one (almost equal)........................................................................................................Trisetum spicatum 2b. Flowerhead is not spikelike but is open and loose; basal leaf sheaths are smooth and the upper glume is much longer than the lower one................................................................................................Trisetum cernuum Trisetum cernuum Trin. Nodding Trisetum Plant: Trisetum cernuum is a native species that is 10-70 cm tall. It is a tuft- forming perennial with few-flowered nodding flowerheads. Leaves and Stem: Sheaths are open. The drooping, flat leaf blades are 5-12 mm wide. The leaves have thin, prominent tips. There are no auricles. The ligules are well developed and 1.5-3 mm long. Flowerhead and Flowers: The flowerhead is widely branched and sparse, bearing a few spikelets at the end of drooping branches. The second or inside glume is much larger than the first and has a sharp tip that extends from two teeth at the top of the glume. The lemmas of the two flowers each have a 10-mm-long bent awn. Habitat: Nodding Trisetum grows in moist woods, forests and stream banks. In the Columbia Basin region it occurs in several lakes around Nelson, at Naskup and along the Pend d'Oreille River. Similar Species: There are two varieties of Nodding Trisetum in British Columbia: cernuum and canescens. Variety cernuum has an open, lax or drooping flowerhead, 6-11 mm-wide leaves and is most often found along the coast; whereas variety canescens has a narrow, interrupted flowerhead, upward-pointing branches and 4-7-mm-wide leaves. Nodding Trisetum resembles Spike Trisetum (T. spicatum). Spike Trisetum and Nodding Trisetum each have awns, but they are differentiated by the flowerhead type and the glumes. The flowerhead of Spike Trisetum is spikelike and the upper glume is not much longer than the lower one; whereas the flowerhead of Nodding Trisetum is open to narrow, nodding but not spikelike, and the upper glume is much longer than the lower one. Trisetum spicatum (L.) Richt. Spike Trisetum Plant: Trisetum spicatum is a native species that grows to 50-70 cm tall. It is a densely tufted perennial with an often-interrupted dense, spikelike flowerhead that is purplish, tawny or silvery coloured. Leaves and Stem: The stem and leaves are often hairy or rough to the touch. The sheath is open and keeled at the upper end. The ligules are 0.5-2 mm high and are ragged along the edge and hairy throughout. Flat or folded leaves are 1.5-5 mm wide and finely hairy. Flowerhead and Flowers: The narrow flowerhead is spike-like and 2-15 cm long, most often purplish, tawny or silvery coloured. The spikelets contain two to three flowers. Almost equal membranelike glumes are rough along the keel and surpass the first flower. Lemmas are rough to the touch and have a bent awn that is 5-6 mm long arising 1.5 mm from between two teeth at the tip. Habitat: Spike Trisetum grows on moist to dry sites in all zones and often occupies rocky sites. It is common throughout the Columbia Basin region and occurs at Windermere, Flathead, Mount Assiniboine Park, Nelson, Yoho National Park and New Denver. Similar Species: Spike Trisetum is highly variable and some authors have recognized several subspecies: but at this time, Douglas et al. (1994) recognize only the one species. Trisetum wolfii Vasey Wolf's Trisetum Plant: Trisetum wolfii is a native species that grows to 40-80 cm tall. It is a perennial that occurs as a loosely tufted form or has a rhizome-bearing form. The flowerhead is a narrow spike that is purplish before complete maturity. Leaves and Stem: The open sheaths feel rough, though they also sometimes have soft hairs. The ligules are 2.5-4 mm high and have a blunt shape and ragged hairs along the margins. Flat leaf blades are 2-6 mm wide. There are no auricles. Flowerhead and Flowers: The narrow spikelike flowerhead has short branches that point upward. Purplish spikelets are two- to three-flowered. Glumes are equal to, or exceeding, the first flower. The blunt lemmas are 4.5-6.5 mm long. The callus has sparse hairs on it. The stem between the flowers is also sparsely hairy. There are no awns, and this feature distinguishes this species from other Trisetum. Habitat: Wolf's Trisetum grows in wet meadows and along streams in the subalpine zones. The only material collected for B.C. is from Mount Assiniboine Park, and that specimen is held in Ottawa. This species is Red-listed by the B.C. Conservation Data Centre. Similar Species: Due to the lack of awns Wolf's Trisetum is fairly easy to distinguish this species from other Trisetum species.

	Copyright © Royal BC Museum All rights reserved