General: Perennial aquatic herb from a fibrous root; stems much branched, submersed, 30-150 cm long, about 1 mm thick.
Leaves: Basal leaves lacking; stem leaves linear, 1-3 cm long, about 0.5 mm wide, in nearly opposite pairs, the base expanded for 3-5 mm and more or less sheathing, the margins minutely toothed, tapering continuously to the slender tips.
Flowers: Inflorescence solitary or a pair of unstalked or nearly unstalked, axillary, unisexual flowers; perianth parts lacking; male flowers with 1-chambered anthers.
Fruits: Achenes, spindle-shaped, about 3 mm long, smooth.
Ponds and marshes in the lowland, steppe and montane zones; frequent in S BC south of 53degreeN, rare northward in E BC to 55degreeN, rare on the Queen Charlotte Islands, E to NF and S to MA, CT, VA. KY, MO, NE, AZ and CA.
The table below shows the species-specific information calculated from original data (BEC database) provided by the BC Ministry of Forests and Range. (Updated August, 2013)
