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GRASSES OF THE COLUMBIA BASIN OF BRITISH COLUMBIA Heather Stewart, Richard Hebda Major Groups of Grasses Table of Contents Glossary Aristida Three-awn This genus of 300 species thrives in stony, arid soils. The name derives from the Latin arista = awn, because many of the species have extremely long awns. There are two species of Aristida occurring in British Columbia, Aristida oligantha (an annual) and Aristida longiseta (a perennial).   Aristida longiseta Steud. var. robusta Merr. Red Three-awn Plant: Aristida longiseta is a native species that grows to 20-40 cm tall. It is a rough, strongly tufted, perennial. The narrow pyramid-shaped flowerhead has open upward-pointing branches and is dominated by long, sharp awns. Leaves and Stem: The sheaths are open and the ligules are less than 0.5 mm high in the front and often appear as a short fringe of hairs. In front of the ligules there are several long hairs (2-3 mm). The inrolled leaf blades are rough and are 1-2 mm wide. Flowerhead and Flowers: The flowerhead is 5-10 cm long and is narrow with few open upward-pointing branches. The glumes are awn tipped. The hardened, flattened callus is sharpely pointed and extends approximately 1 mm long. The lemma tip splits into three 5-8-cm-long awns, with the lateral awns widely separated from the central one. The overall impression of this grass in flower is one of many diverging awns. Habitat: Red Three-awn grows on dry grassland sites and bare rocky soils in the steppe and montane zones. In the Columbia Basin region the species occurs at Kimberley and Midway. Similar Species: Red Three-awn is a distinctive species. The diverging awns are sometimes confused with Needle-and-thread Grass (Stipa comata), which has long awns but only one awn per spikelet.

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