Vines, perennial, semiwoody. Leaves alternate. Inflorescences terminal or axillary panicles, mostly 50–100-flowered. Flowers epigynous (hypogynous in all other genera); sepals 4(–5); stamens 15–20; carpels (3–)4, connate at least halfway proximally; ovary inferior (3–)4-locular, eventually 1-locular by abortion of septa; style 1; stigmas (3–)4. Fruits cypselas, turbinate, crowned by winglike sepals. Seed 1, by abortion of other (2–)3 ovules.
North America, Mexico, Central America.