Distribution: Alaska to California, east from the coast to Manitoba and the Great Lakes region
Habitat: Pond margins, marshes and ditches at low elevations
Flowers: June - July
Conservation Status: Not of concern
Robust annuals, scabrous but otherwise glabrous, the culms to 1 m. tall, hollow, erect, often stoloniferous.
Sheaths open; ligules 6-11 mm. long, acuminate, pubescent, usually lacerate; blades 5-10 mm. broad, flat.
Inflorescence narrow, congested, up to 3 dm. long, of racemose spikes; spikes 1-2 cm. long; spikelets 1-flowered, articulate below the glumes; glumes about 3 mm. long, subequal, strongly compressed and inflated, 3-nerved, semicircular, acute; lemmas equaling the glumes but much narrower; paleas slightly shorter than the lemmas, 2-nerved; stamens 3; lodicules 2, 1 mm. long.