Kosteletzkya pentacarpos is a perennial herb to 1 m tall, stems rough-hairy.
Leaves alternate, 6-15 cm long, egg-shaped, with two lateral lobes, tip pointed, base lobed, margin coarsely toothed, dull gray-green, rough-hairy, upper leaves becoming bract-like, lance-shaped.
Flowers pink, showy, petals 2-4.5 cm long, 3 cm wide, egg-shaped, calyx to 1.3 cm, accompanied by small, linear bracts to 1 cm long, stamens and stigma united in a central column to 2.5 cm long, ovary superior.
Fruit dry, hollow, a hairy, rounded, somewhat flattened capsule of 5 one-seeded segments.
Wetland status: OBL.
Frequency in NYC: One site known in NYC, possibly extirpated.
Habitat: High salt, and brackish marshes. Mostly a southern plant.