Scheuchzeria palustris ssp. americana

General:
Perennial, aquatic herb from long rhizomes, rooting at the nodes; stems 10-40 cm tall.

Leaves:
Basal leaves linear, 10-40 cm long, parallel-lined, sheathing, persistent; stem leaves reduced upwards, the ligules 1-10 mm long, the blades erect, 1-3 mm wide.

Flowers:
Inflorescence of 3- to 12-flowered racemes, the greenish-white flowers on stalks up to 2.5 cm long; perianth segments 6, oblong, 1-nerved, about 3 mm across; stamens 6.

Fruits:
Follicles, 5-10 mm long, beaked, the beaks up to 1 mm long; seeds 4-5 mm long.

Source:  The Illustrated Flora of British Columbia