General:
Annual or biennial herb from a taproot, smooth; stems erect to ascending, 20-80 cm tall, freely branched.

Leaves:
Basal leaves withered at flowering time; stem leaves several to many, 3-10 cm long, pinnately compound, with stipules fused to base of long leaf-stalks and forming membranous margins; leaflets 9 to 17, oblong-elliptic, 0.5-2 cm long, pinnately cleft into linear segments; stipules of lower leaves fused to leaf-stalk below, free at the tip, entire, those of the upper leaves free, leaflet-like, pinnately cleft.

Flowers:
Inflorescence a dense, cylindric to globe-shaped, long-stalked spike, the spike 0.5-3 cm long, of numerous small flowers; corollas absent; calyces green, 4-lobed, the lobes egg-shaped, 2-3 mm long; ovaries superior; stamens usually 2, the filaments thread-like, about as long as the calyx-lobes.

Fruits:
Achenes, enclosed in the 4-angled, thick-edged but barely winged, weakly net-veined, smooth hypanthium.

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:
Poteridium annuum (Nutt. ex Hook.) Spach
Sanguisorba occidentalis Nutt.