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

General:
Aquatic herb, usually without roots; stems freely branching, 0.3-4.0 m long.

Leaves:
Stem leaves submerged, in whorls of 5-12, 2-3 times forked into linear or threadlike segments, these often stout, stiff and spiny-toothed.

Flowers:
Inflorescence of solitary, minute, axillary flowers; petals lacking; sepals 3-15, sometimes petal-like; stamens 12-16.

Fruits:
Achenes usually lacking, if present then much flattened, 4-6 mm long, ellipsoid, wingless with a persistent style and 2 basal spines.