E-Flora BC: Electronic Atlas of the Flora of British Columbia

General:
Annual or biennial (sometimes perennial) grass from fibrous roots, often flowering in the first season; stems smooth to hairy, 30-100 (130) cm tall.

Leaves:
Sheaths closed to near the tops, sometimes smooth but usually soft-hairy at least at the throats and often copiously soft-hairy to greyish short-hairy; blades (2) 3-12 (15) mm wide, flat to somewhat in-rolled, smooth to rough or soft-hairy; ear-shaped lobes at the leaf-bases barely 0.5 mm long; ligules smooth to soft-hairy or jagged, 1-3 (6) mm long.

Flowers:
Inflorescence a somewhat narrow panicle, (5) 10-25 (30) cm long, the branches erect or ascending, less commonly spreading to reflexed; spikelets (4-) 5- to 10- (12-) flowered, strongly compressed, (1.5) 2-3 (4.5) cm long; florets mostly small, closed, self-fertilized; glumes lanceolate, keeled, the lower ones usually 3-nerved, 5-9 mm long, the upper ones (5) 7-nerved, up to nearly 2 times as long as the lower ones; lemmas smooth to rough short-hairy or strongly hairy, keeled, 10-13 mm long, shallowly bidentate at the tips, awned, the awns straight, 3-15 mm long; anthers 3, included within the lemmas to partially or completely exserted, 1-4 (5) mm long.

Notes:
This is an extremely variable species consisting of numerous phases with mainly sympatric ranges. Two phases, var. linearis (with copiously soft-hairy sheaths and blades) and B. marginatus (with shorter awns), are sometimes given formal recognition. Hitchcock (1969) recognizes var. linearis and Hitchcock and Chase (1951) and Pavlick (1995) recognize B. marginatus, but there is no compelling evidence that they are taxonomically different. I have followed the treatments by Hitchcock (1969), Welsh (1974), Holmgren and Holmgren (1977) and Wilken and Painter (1993), which submerge B. marginatus within B. carinatus.