(bittersweet, or staff vine) is a family of mostly tropical plants, limited in the US to 16 genera and 50 species. The majority are shrubs, trees or vines, though a few are herbs. Leaves are undivided, stalked, often leathery or shiny, and either alternate or opposite. Flowers usually form in clusters, elongated or branched. Individual flowers have five (less often four) sepals and petals, and the same number of stamens, usually radiating outwards between the petals, and attached at the base to the edge of a raised nectar disk. Flowers tend to be relatively small.