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

General:
Perennial tufted or matted grass from fibrous roots; stems 5-30 cm tall.

Leaves:
Sheaths smooth; blades 2-15 cm long, 1-3 mm wide, flat or in-rolled; ligules 1-3 mm long, slightly rough short-hairy on the outside.

Flowers:
Inflorescence open or more or less constricted in age, ellipitical to narrowly egg-shaped, 1.5-10 cm long, the branches spreading or appressed, the lower branches 0.5-7 cm long; spikelets numerous; glumes 1.6-2.3 mm long; lemmas 1.5-2.3 mm long, awnless; the callus hairs absent or sparse to 0.5 mm long; rachillas present behind the paleas as minute bristles 0.1-0.6 mm long or occasionally absent and variable even within the inflorescence, hairless or with small tufts of hairs at the tips; paleas present, at least 1/2 as long as the lemmas; anthers 0.6-0.8 mm long.

Notes:
The taller plants with the more open inflorescence have usually been separated out as A. thurberiana A.S. Hitchc. but are here included in A. humilis because of the existence of intermediates. A. variabilis, another dwarf alpine species, closely resembles A. humilis in the field and should be confirmed by its lack of paleas.