Callitriche palustris is an annual herb, small aquatic or rooted in mud, to 20 cm long, often in dense patches, rooting from lower nodes.
Leaves opposite, those below water, linear, to 1.5 cm, leaves above water spatulate, crowded into a small rosette at stem tips, margins entire;
Flowers (use hand lens) in leaf axils, 1 stamen, one 4-lobed ovary, with two stigmas, tiny, whitish fleshy bracts from base of female flower, found flowering late May.
Fruit: to 0.14 cm, flattened, broadly grooved along edges and faces, margins of grooved sharp edged to slightly winged; April-Nov.
Wetland status: OBL.
Frequency in NYC: Very infrequent.
Habitat: Shallow, still water or on mud.
Notes: Plants eaten by muskrats.