Epilobium leptophyllum is a perennial herb, 20-100 cm tall, from slender stolons, stems arising from bulb-like swelling at tip of stolon.
Leaves opposite, the uppermost sometimes alternate, stalkless, often with small leafy clusters in axils; blade 2-7 cm long, 0.1-0.7 cm wide, hairy.
Flowers white to pink, 0.4-0.6 cm long, 4-parted, petal tip notched; flowering stems branched, hairy.
Fruit dry, linear, splitting open to release numerous plumed seeds.
Wetland status: OBL.
Frequency in NYC: Very infrequent.
Habitat: Open marshes, bogs, soil pH 4-6.5 (USDA, NRCS 2006).