According to Ceska and Ceska (2010): "Western Water-Milfoil occurs from California to the Lower Fraser Valley in British Columbia; there it forms dense stands in sloughs of the Fraser River and its tributaries. Easily recognized by deep green colour, dense foliage with additional numerous leaves outside the whorls. Winter buds absent. "

General:
Perennial aquatic from a short rhizome; stems stout, olive green, 2-3 mm wide, 60-120 cm long.

Leaves:
In whorls of 4 to 6, with some additional alternate leaves scattered outside the whorls; emersed leaves linear, the lower ones pinnately dissected into capillary divisions, the upper ones deeply sharp-toothed or entire; winter buds absent.

Flowers:
Perfect or the lower ones female and upper ones male; bracteoles minute, not more than 0.7 mm long; petals white, 1-2 mm long; stamens 4.

Fruits:
Mericarps, 4, laterally compressed, 1.5-2 mm long, with smooth dorsal ridges.

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