General:
Perennial, densely to loosely tufted grass from fibrous roots and rhizomes; stems usually decumbent, 7.5-60 cm tall/long.

Leaves:
Sheaths hairless, margins open 1/2-3/4 their length; sterile shoots mainly breaking through the sheath bases; basal bladeless leaves present; blades 1-4 mm wide, flat or folded; ligules (1) 2-7 mm long, the tips blunt or rounded to sharp-pointed, entire or torn, backs smooth or slightly rough.

Flowers:
Inflorescence a lax to erect panicle, (2) 3.5-15 cm long, sparse, egg-shaped to broadly pyramidal, usually open; lowermost internodes less than 1.5 (3) cm long, the branches 1 to 5 per node, ascending or widely spreading, round, smooth or slightly to moderately rough, spikelets not crowded, longest lowermost branches 2/5-3/5 the length of the panicle; spikelets laterally compressed, 4-8 mm long, (2-) 3- to 6-flowered, sometimes with bulbils; glumes lanceolate to broadly lanceolate, keels indistinct, smooth or slightly rough near the tips, the lower ones 3-nerved, the upper usually nearly equalling to slightly exceeding the lower lemmas; rachillas smooth, hairless or sparsely minutely soft to long silky-hairy; lemmas lanceolate to broadly lanceolate, 3.5-7 mm long, the tips sharp-pointed, margins broadly translucent, surface smooth, keel and marginal nerves long silky-hairy, lateral nerves silky-hairy, mostly short silky-hairy between the nerves, lateral nerves prominent; calluses sparsely to copiously hairy; palea keels silky-hairy most of the length (rarely nearly hairless), minutely soft-hairy (or with at least a few, minute, straight hairs) between the keels; flowers bisexual (some appearing female due to aborted anthers); anthers sometimes aborted late in development or if present, 1.4-2.5 mm long.

Notes:
Two subspecies occur in BC:

1. Spikelets mostly greater than 6 mm long; lower lemmas 4.5-6 mm long; stem leaf blades often flat and more than 2 mm wide................... ssp. lanata (Scribner & Merr.) Soreng

1. Spikelets less than 6 mm long; lower lemmas 3-4.5 mm long; stem leaf blades mostly folded and less than 2 mm wide................... ssp. arctica

Source:  The Illustrated Flora of British Columbia

If more than one illustration is available for a species (e.g., separate illustrations were provided for two subspecies) then links to the separate images will be provided below. Note that individual subspecies or varietal illustrations are not always available.

Illustration Source:  The Illustrated Flora of British Columbia

Synonyms and Alternate Names:
Poa arctica subsp. longiculmis Hultén
Poa arctica subsp. williamsii (Nash) Hultén
Poa arctica var. glabriflora Rosh.
Poa arctica var. vivipara Hook.
Poa cenisia var. arctica (R. Br.) K. Richt.
Poa longipila Nash
Poa williamsii Nash