Distribution: Occasionally escaping from cultivation, but rarely becoming established in Washington; occasionally escaped from cultivation in many areas in North America.
Habitat: Waste ground.
Conservation Status: Not of concern
Dioecious, twining, herbaceous, perennial vines from rhizomes, the stems rough, up to 6 m. long.
Leaves opposite, deeply 3- to 5-lobed, the blades cordate-based, scabrous, strongly serrate, 4-10 cm. long.
Staminate flowers in panicles in axillary inflorescences; perianth segments 5, distinct, opposed by 5 stamens; pistillate inflorescences cylindric-ovoid, greenish-yellow, 3-5 cm. long, with yellow glands; pistillate flowers in pairs in bracteate spikes, the bracts entire, hiding the flowers; styles 2.
Achenes hidden by the bracts.