Plant: annual, mostly submerged aquatic or terrestrial herb Leaves: polymorphic; submerged leaves linear, 1-15 mm long, 0.5-1.0 mm wide, the margins entire, the apices bifid or emarginate with the single nerve often extending to a callous point, the bases clasping the stem, the basal pairs usually separated but connected by a ridge or wing at the node, or less often adjoining; floating or terrestrial leaves petioled, 3-nerved, obovate to oblanceolate to spatulate, 1-15 mm long, 1-5 mm wide, the apices rounded to slightly retuse, the bases as above, the surface covered with minute scales and appearing punctate INFLORESCENCE: with usually single staminate and pistillate flowers in each axil Flowers: subtended by a pair of whitish inflated bracteoles, 0.5-1.5 mm long, usually deciduous in fruit; styles 1-6 mm long, erect or spreading, often persistent Fruit: nutlets, brown at maturity, sessile, 0.5-1.3 mm long, 0.6-1.1 mm wide, broadly-obovate, usually deeply notched between the carpels, overall appearing cordate, the margins wingless (immature material may appear wing-like when the seed fails to fill the mericarp, the unexpanded margin appears thin and wing-like, but pitted like the surface of the mericarp), rounded, the groove between carpels very shallow or inconspicuous, not at all sharp-edged; surface pitted, but the pits not obviously aligned in vertical rows Misc: Lakes, ponds and slow-moving streams; 900-2750 m (3000-9000 ft); Feb-Aug (fr. May-Oct) REFERENCES: Ricketson, Jon. 1995. Callitrichaceae. J. Ariz. – Nev. Acad. Sci. 29(l): 15.