Rhamneae
A natural order of erect or climbing, often prickly, very rarely tendrilled or glandulose trees, shrubs, or very rarely herbs, inhabiting warm and tropical regions. Flowers green or yellowish, hermaphrodite, rarely polygamous, dicecious, small, usually disposed in axillary, loose or dense-flowered, sometimes unilateral cymes; calyx tube obconical, turbinate, urceolate, or cylindrical, the limb of four or five erect or recurved lobes; petals four or five, inserted at the throat of the calyx, emarginate or lobed, sessile or clawed, or absent; stamens four or five, opposite to, and inserted with, the petals; filaments subulate or filiform, rarely dilated; anthers versatile, sometimes ovoid, with longitudinal dehiscence, sometimes reniform and one-celled by confluence of the cells at the top, and opening into two valves by an arched slit; disk perigynous, rarely absent. Fruit capsular or drupaceous, three, rarely one to four-celled. Leaves simple, stipulate, rarely exstipulate, opposite or nearly so, often coriaceous, entire or serrated (in Colletieae often absent); stipules small, usually deciduous, sometimes changed to thorns. The most useful genera, from an economic point of view, are Rhamnus and Zizyphus, the species of which yield medicinal juices, &c. Rhamnus davuricus and R. tinctorius yield the famous Green Indigo, the Lo-Kao of China. The order comprises thirty-seven genera, and about 430 species. Examples: Hovenia, Paliurus, Pomaderris, and Rhamnus.