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

General:
Perennial tufted grass from tough, underground, scaly rhizomes to 25 cm long; stems 20-120 cm tall.

Leaves:
Sheaths smooth; blades 4-10 cm long, 3-8 mm wide, usually flat; ligules longer than wide, 2-6 mm long.

Flowers:
Inflorescence open, broadly egg-shaped, 8-25 cm long, the branches spreading, the lower branches 4-7 cm long, but mixed with many short branches resulting in a crowding of the spikelets to the branch base (except in shade plants), the branches spreading broadly at flowering time and remaining so; glumes 1.7-3.2 mm long; lemmas 1.5-2.2 mm long, awnless or rarely with short, straight awns from near the tips; callus hairs sparse, up to 0.5 mm long; rachillas absent; paleas 0.7-1.4 mm long, as least 1/2 as long as the lemmas; anthers 1-1.4 mm long.

Notes:
This species was formerly combined with A. stolonifera under the illegitimate name A. alba. It is distinguished from A. stolonifera by its underground rhizomes, its open inflorescence and tolerance of much drier habitats.