Rorippa sylvestris is a perennial herb, colonial from creeping underground shoots, stem erect to 60 cm tall, branched above.
Leaves stalked, a basal rosette in young plants, stem leaves alternate, lower leaves to 20 long, 2 cm wide, deeply pinnately divided, lobes narrow with pointed tips, margins toothed, reduced upward.
Flowers bright yellow, 4-parted, petals to 0.5 cm long, widest above middle, twice as long as sepals, stalks to 1 cm long; blooming May-June.
Fruit capsules linear, 2-parted, to 1.5 x 0.1 cm, often seedless; fruiting to Sept..
Wetland status: FACW.
Frequency in NYC: Very infrequent.
Habitat: Open wet to moist soil.