General:
Annual herb from a taproot; stems erect or ascending, solitary, usually freely branched, smooth, angled, 1-15 cm tall.

Leaves:
Basal leaves lacking; stem leaves alternate, linear, the blades 10-40 mm long, unstalked; stipules ragged, 4-8 mm long.

Flowers:
Inflorescence a terminal, spikelike raceme, closely crowded and usually overlapping, in groups of 1-4 in the axils of white- or green-margined floral bracts; perianths 2-3 mm long, white to red, unequally 5-lobed 2/3 the distance to the base.

Fruits:
Achenes 3-angled, brown to nearly black, dull or shiny, smooth or longitudinally lined, 1.5-2 mm long, sometimes difficult to separate.

Notes:
Two subspecies occur in our region.

1. Floral bract margins white; achenes brown to nearly black; usually dull, longitudinally grooved......................... ssp. confertiflorum (Piper) Hickman

1. Floral bract margins green; achenes brown, usually shiny, smooth......................... ssp. kelloggii (Greene) Hickman

Source:  The Illustrated Flora of British Columbia

Synonyms and Alternate Names:
Polygonum confertiflorum Nutt. ex Piper
Polygonum imbricatum Nutt.
Polygonum kelloggii var. confertiflorum (Nutt. ex Piper) Dorn
Polygonum watsonii Small