This section is from the book "Handbook Of Hardy Trees, Shrubs, And Herbaceous Plants", by W. Botting Hemsley. Also available from Amazon: Handbook of hardy trees, shrubs, and herbaceous plants.
Herbs or shrubs, usually of climbing or trailing habit, and often furnished with tendrils and thorns. Leaves simple, alternate, distinctly petiolate, net-veined and usually ribbed. Flowers small, green or yellowish green, hermaphrodite or unisexual, generally in axillary clusters or umbels, rarely solitary. Perianth inferior, six-partite, segments similar. Stamens 6. Fruit superior, baccate, 1- to 3-celled, 1- to 3-seeded. There are two or three genera, comprising upwards of 100 species, chiefly belonging to the following genus and widely dispersed in temperate and tropical regions.