Oleaceae

The Oleaceae are a family of flowering plants in the order Lamiales. It presently comprises 26 genera, one of which is recently extinct. The 25 extant genera include Cartrema, which was resurrected in 2012. The number of species in the Oleaceae is variously estimated in a wide range around 700. The Oleaceae consist of shrubs, trees, and a few lianas. The flowers are often numerous and highly odoriferous. The family has a subcosmopolitan distribution, ranging from the subarctic to the southernmost parts of Africa, Australia, and South America. Notable members of the Oleaceae include olive, ash, jasmine, and several popular ornamental plants including privet, forsythia, fringetrees, and lilac. The following list contains all 25 genera recognized in the most recent (2004) revision of the family. It also includes Cartrema, the name of which was resurrected in 2012. Linociera is not included, even though some authors continue to recognize it. Linociera is not easy to distinguish from Chionanthus, mostly because the latter is polyphyletic and not clearly defined. The type genus for Oleaceae is Olea, the olives. Recent classifications recognize no subfamilies, but the family is divided into five tribes. The distinctiveness of each tribe has been strongly supported in molecular phylogenetic studies, but the relationships among the tribes were not clarified until 2014. The phylogenetic tree for Oleaceae is a 5-grade that can be represented as {Myxopyreae }. The major centers of diversity for Oleaceae are in Southeast Asia and Australia. There are also a significant number of species in Africa, China, and North America. In the tropics the family is represented in a variety of habitats, from low-lying dry forest to montane cloud forest. In Oleaceae, the seed dispersal is almost entirely by wind or animals. In the case that the fruit is a berry, the species is mostly dispersed by birds. The wind-dispersed fruits are samaras. Some of the older works have recognized as many as 29 genera in Oleaceae. Today, most authors recognize 25 or 26, but this number will change because some of these genera have recently been shown to be polyphyletic. Estimates of the number of species in Oleaceae have ranged from 600 to 900. Most of the species number discrepancy is due to the genus Jasminum in which as few as 200 or as many as 450 species have been accepted. In spite of the sparsity of the fossil record, and the inaccuracy of molecular-clock dating, it is clear that Oleaceae is an ancient family that became widely distributed early in its history. Some of the genera are believed to be relictual populations that remained unchanged over long periods because of isolation imposed by geographical barriers like the low-elevation areas that separate mountain peaks. Members of the family Oleaceae are woody plants, mostly trees and shrubs; a few are lianas. Some of the shrubs are scandent, climbing by scrambling into other vegetation.