Distribution: Distributed widely throughout Washington; widely distributed throughout North America.
Habitat: Marshes, ponds and shallow slow-flowing water, sea level to mid-elevations in the mountains.
Conservation Status: Not of concern
Monoecious, perennial herbs of wet places from extensive rhizomes, the stems 1-3 m. tall, erect, cylindrical and pithy.
Leaves alternate, sheathing, linear, the blades 8-20 mm. broad, grayish-green.
Flowers naked in terminal, cylindrical, spike-like inflorescences, the staminate above the pistillate, the two portions contiguous; staminate flowers consisting of 2-5 stamens borne directly on the main axis, intermixed with slender hairs; pistillate flower a single, 1-celled pistil; pistillate section 12-30 mm. thick, brown, the surface minutely pebbled; abortive ovaries pear-shaped.
Fruit dry, 1 mm. long, ellipsoid.