Rhamnaceae

The Rhamnaceae are a large family of flowering plants, mostly trees, shrubs, and some vines, commonly called the buckthorn family. Rhamnaceae is included in the order Rosales. The family contains about 55 genera and 950 species. The Rhamnaceae have a worldwide distribution, but are more common in the subtropical and tropical regions. The earliest fossil evidence of Rhamnaceae is from the Late Cretaceous. Fossil flowers have been collected from the Upper Cretaceous of Mexico and the Paleocene of Argentina. Leaves of family Rhamnaceae members are simple, i.e., the leaf blades are not divided into smaller leaflets. Leaves can be either alternate or opposite. Stipules are present and modified into spines in many genera. In some (e.g. Paliurus spina-christi and Colletia paradoxa) spectacularly so. Colletia stands out by having two axillary buds instead of one, one developing into a thorn, the other one into a shoot. The flowers are radially symmetrical. There are 5 (sometimes 4) separat......read more on Wikipedia.