Distribution: Chiefly east of the Cascades in Washington; occurring throughout much of North America.
Habitat: Moist bottomlands and thickets.
Conservation Status: Not of concern
High-climbing, annual vine, monoecious, with branched tendrils.
Leaves alternate, simple, petiolate, 5-15 cm. long, slightly rough, palmately 5-lobed, the triangular-acute lobes remotely toothed.
The staminate flowers in few-flowered, narrow panicles on short peduncles from the leaf axils; the pistillate flowers usually solitary from the same axils; corolla with a short tube and 6 spreading, narrowly lanceolate lobes 3-6 mm. long and 1 mm. wide; sepals 6, small and bristle-like, inserted in the sinuses of the corolla; stamens 3, ovary 2-celled.
Fruit bladdery-inflated, 3.5-5 cm. long, weakly spiny; seeds flattened, ovate, 1.5 cm. long.