General:
Perennial herb from a taproot; stems 1 or more, erect to decumbent, glabrous, 30-60 cm tall/long.

Leaves:
Basal leaves several, oblong-lanceolate, 7-9 cm long, 1-2 cm wide, glabrous; stem leaves opposite, 4-10 pairs, becoming lanceolate and only slightly reduced above, mostly 4-9 cm long, broadly short-stalked, the base sheathing; stipules lacking.

Flowers:
Inflorescence of 3-30 flowers in densely crowded clusters; petals 5, white to more usually pink or red, with narrow claws about equalling the calyces, the blade more or less egg-shaped, 6-10 mm long, wavy-toothed; sepals 5, green below and often violet above, united, forming a glabrous tube about 15 mm long, about 40-nerved.

Fruits:
Capsules oblong, 9-13 mm long, 4-valved; seeds compressed, concave on one side.

Source:  The Illustrated Flora of British Columbia