General:
Perennial amphibious herb from a shallow creeping rhizome, smooth throughout; stems trailing to ascending, 10-70 cm long/tall, rooting at the lower nodes, simple or branched, somewhat fleshy.

Leaves:
Opposite, short-stalked, lanceolate to egg-shaped, 1-5 (8) cm long, usually distinctly toothed.

Flowers:
Inflorescences several long, open, opposite, stalked racemes arising from the axils of upper leaves, the racemes of 5 to 25 stalked flowers, the flower stalks much longer than the linear bracts; corollas blue, saucer-shaped, 5-10 mm across, irregularly 4-lobed, the lobes much longer than the short tube, the lowest lobe narrower than the others; calyces 2-5 mm long, deeply 4-lobed, the lobes lanceolate to egg-shaped; styles 2-4 mm long, exserted; stamens 2.

Fruits:
Capsules, 3-4 mm long, a little wider than long, plump, somewhat globe-shaped, not or scarcely notched at the tip; seeds numerous, flattened, about 0.5 mm long.

Source:  The Illustrated Flora of British Columbia