General:
Perennial, aquatic herb from weak rhizomes; stems floating, 20-80 cm tall.

Leaves:
Alternate, limp, grasslike, unkeeled, flat, floating, linear with sheathing bases, 10-50 cm long, 1-5 mm wide.

Flowers:
Inflorescence simple, of 1 to 4 female heads below and 1 (rarely 2) male head above, the heads globe-shaped, the female heads 0.5-1.4 cm wide, at least some borne above the leaf axils, unstalked above, stalked below; perianth segments 6, attached near the top of the flower stalk; stigma 1; anthers less than 0.8 mm long.

Fruits:
Achenes, 2-5 mm long, constricted at the middle, beaked or beakless, the beaks less than 0.5 mm long, straight; seeds 1.

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