Rorippa nasturtium-aquaticum is a perennial aquatic herb, on wet mud, floating or submersed, rooting along stem.
Leaves alternate, pinnately divided, 3-9 rounded segments, terminal segment much larger than laterals.
Flowers white, to 0.5 cm wide, 4-parted; stalks to 1.5 cm long, blooming May-July.
Fruit capsules linear, to 2.5 cm long, curving, beak 0.1 cm.; fruiting to Oct.
Wetland status: OBL.
Frequency in NYC: Very infrequent.
Habitat: Streams, clear, quite water.
Notes: The edible, commercially grown watercress.