General: Perennial, aquatic herb from long rhizomes; stems usually submerged, 80-150 cm tall.
Leaves: Alternate, limp, unkeeled, usually floating, linear, ribbon-like, 60-100 cm long, 3-11 mm wide.
Flowers: Inflorescence branched, of 2 to 4 female heads below and 1 to 6 male heads above, the heads globe-shaped, unstalked, the female heads 1.5-2.3 cm wide, axillary and subtended by conspicuous leaflike bracts; perianth segments 6, spoonlike, often with a dark spot at the tips, attached near the base of the flower stalk; stigma 1; anthers about 0.4-0.8 mm long.
Fruits: Achenes, 2-5 mm long, unstalked, more or less constricted at the middle, beaked, the beaks 2-3.5 mm long, curved; seeds 1.
Ponds, lakeshores and slow-moving streams in the lowland and montane zones; rare in BC south of 55 degrees N; circumpolar, E disjunctly to NF and S to ME, MA, PA, MI, WI, MN, ID and WA; Eurasia.
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)
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