Woody climbers or perennial herbs. Leaves opposite, simple, ternate or pinnate; petioles usually tendril-like. Plants dioecious or flowers bisexual. Inflorescence a short panicle, or flowers solitary; peduncles often with a pair of narrow bracteoles near midway; sepals 4(–8) petal-like; petals absent; stamens numerous, staminodes sometimes present in both male and female flowers; carpels numerous, 1-ovulate; style persistent, often long and plumose. Achenes forming a globular head at maturity.
About 250 species of temperate regions; 8 species recognized for Australia, 1 naturalised (some taxa currently regarded below species level probably warrant recognition as species).