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

General:
Perennial, aquatic herb from long rhizomes; stems lax, usually floating, 30-40 cm tall.

Leaves:
Alternate, limp, not keeled, usually floating, linear with sheathing bases, 100-120 cm long, 2-6 (8) mm wide.

Flowers:
Inflorescence simple, of 2 to 4 female heads below and 2 to 5 (8) male heads above, the heads globe-shaped, the female heads 1-2 cm wide, at least some borne above the leaf axils and subtended by conspicuous leaflike bracts; perianth segments 6, scalelike, attached near the top of the flower stalk; stigma 1; anthers about 1 mm long, 0.5 mm wide.

Fruits:
Achenes, 3-7 mm long, constricted at the middle, reddish to brownish at base prior to drying, beaked, the beaks 1.5-2.2 mm long, straight or slightly curved, the stalks 1-1.5 mm long; seeds 1.

Notes:
This is a highly variable species in which different forms are often treated as species (e.g., Hitchcock and Cronquist 1973) or infraspecific taxa (e.g., Brayshaw 1985). Packer (1983b) has shown that there is no justification for recognizing more than a single, variable species, at least until adequate research has shown otherwise.