Sicyos angulatus is an annual vine, stems sticky-hairy, climbing to over 3 meters by 3-forked tendrils opposite each leaf; seedling leaves very large about 10 cm long, 4 cm wide, fleshy, mid-May.
Leaves alternate, broad, with 3-5 shallow, toothed lobes, tips pointed, base deeply, round-lobed.
Flowers whitish, small, petals united, 5-lobed, 0.8-1 cm wide, sexes separate on same plant (monoecious); male flowers ca 1 cm, in unbranched clusters; female flowers in small, round, dense clusters both on long stems in leaf axils; blooming and fruiting July-Sept.
Fruit becoming dry, hollow, spiny-bristly, 2 cm long, 1-seeded, oval, drying bladder-like, in dense round clusters of 3-20.
Wetland status: FACU.
Frequency in NYC: Occasional.
Habitat: Moist second growth, flood plains, edges, open areas or part shade, climbing on other vegetation.
Notes: differentiated from Echinocystis lobata by its hairy stems, 5-lobed flowers and small, bristly fruit, in dense clusters.