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

General:
Perennial submersed aquatic from a rhizome; stems slim, 1-2 mm wide, dark reddish-green, forming dense stands of more or less uniform height, 30-70 cm tall.

Leaves:
Partly in whorls of 3 to 6, and partly scattered alternate; pinnate, the divisions finely capillary in 5 to 7 opposite or subopposite pairs, with minute black glands in the axils; winter buds absent.

Flowers:
Unisexual, solitary in the axils of the leaves; petals 4, purplish, oblong; stamens 4, anthers minute, abortive; styles 4, short.

Fruits:
Mericarps, 4, angular, 2 mm long, 1.5 to 2 mm wide, with tiny warts on the dorsal ridge.