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.
Shrubs or trees with a tough fibrous bark, or rarely herbaceous. Leaves simple, entire, opposite or alternate. Flowers usually bisexual, in terminal or axillary spikes or heads, sometimes involucrate, rarely solitary. Perianth inferior, tubular-cam-panulate; limb usually 4-lobed, lobes imbricate in bud. Stamens commonly 8, and in two series, sometimes 4 or 2, and opposite the perianth-lobes. Fruit a berry or drupe or dry nut, 1-celled 1-seeded; seed pendulous. Grenera about 40, including 300 species. Rare in the northern hemisphere, abundant at the Cape of Good Hope, in Australia and South America.