Plant: Annual, aquatic (usually wholly submerged) herb Leaves: 1-nerved, linear-lanceolate, uniform, 5-25 mm long, 0.5-1.5 mm wide, usually dark metallic green with narrow white, entire margins, the apices usually bifid or broadly notched, bases clasping the stem, the base pairs often overlapping but never connected by a wing at the node INFLORESCENCE: usually a single flower in each axil Flowers: without floral bracteoles; styles 1-6 mm long, usually longer than the ovary, sharply reflexed, soon breaking off and leaving a persistent short base between the tips of the developing fruit Fruit: separating at maturity into 4, 1-seeded nutlets, brown at maturity, sessile or shortly pedicellate, 1.1-1.6 mm long, 1.2-1.8 mm wide, obovate, flattened or slightly rounded, the surface obscurely and irregularly pitted, the carpel margins flattened appearing wing-like, the groove between carpels deep and narrow between the wings Misc: Lakes, ponds and slow moving streams; 2700 m (8900 ft); Jun-Sep (fr. Aug-Oct)