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

General:
Annual herb from a rhizome; stems prostrate to erect, solitary from the rooted rhizome, few to numerous, 30-100 cm tall/long.

Leaves:
Basal leaves lacking; stem leaves alternate, lanceolate, mostly smooth, 5-10 cm long, short-stalked; stipules sparsely hairy, 10-15 mm long, sometimes fringed with bristly hairs at the tops.

Flowers:
Inflorescence of axillary and terminal, spikelike, interrupted racemes; perianths greenish with white margins, glandular-dotted, 5-lobed to about 1/2 the distance to the base; stamens usually 8.

Fruits:
Achenes, 2- to 3-angled, deep brownish-black to black, smooth, shiny.

Notes:
Closely related to P. hydropiper.