General:
Annual herb from a taproot; stems erect, simple to freely branched, 0.3-2.0 m tall, grooved, often reddish, glabrous to short-hairy or sparsely hairy below the flowers.

Leaves:
Alternate or opposite, leaf blades 2.5-14 cm long, glabrous or nearly so, egg-shaped to deltoid-elliptic.

Flowers:
Inflorescence in terminal and axillary spikes; bracts linear-lanceolate and spiny; sepals unequal; stamens 3-4.

Fruits:
Capsules opening along an "equator", the top coming off like a lid, 1-seeded; seeds 1 mm long, lens-shaped.

Source:  The Illustrated Flora of British Columbia