Oleaceae - WikiHQ

Oleaceae (), also known as the olive family or sometimes the lilac family, is a taxonomic family of flowering shrubs, trees, and a few lianas in the order Lamiales. It presently comprises 28 genera, one of which is recently extinct. The 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 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 include olive, ash, jasmine, and several popular ornamental plants including privet, forsythia, fringetrees, and lilac.

Genera

The following 29 extant genera are recognized in the family Oleaceae. 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.

Tribe Myxopyreae
Myxopyrum Blume
Dimetra Kerr
Nyctanthes L.
Tribe Forsythieae
Abeliophyllum Nakai – white forsythia
Forsythia Vahl – forsythia
Tribe Fontanesieae
Fontanesia Labill.
Tribe Jasmineae
Chrysojasminum Banfi
Menodora Humb. & Bonpl.
Jasminum L. – jasmine
Tribe Oleeae
Subtribe Ligustrinae
Syringa L. – lilac
Ligustrum L. – privet
Subtribe Schreberinae
Comoranthus Knobl.
Schrebera Roxb.
Subtribe Fraxininae
Fraxinus L. – ash
Subtribe Oleinae
Cartrema Raf.
Chengiodendron
Chionanthus L. – fringe tree
Forestiera Poir. – swamp privet
Haenianthus Griseb.
Hesperelaea A.Gray
Nestegis Raf.
Noronhia Stadman ex Thouars
Notelaea Vent.
Olea L. – olive
Osmanthus Lour. – osmanthus
Phillyrea L. – mock-privet
Picconia D.C.
Priogymnanthus P.S.Green
Tetrapilus

Overview

The type genus for Oleaceae is Olea, the olives. Recent classifications recognize no subfamilies, but the family is divided into five tribes. The phylogenetic tree for Oleaceae is a 5-grade that can be represented as {Myxopyreae [Forsythieae (Fontanesieae <Jasmineae + Oleeae>)]}.

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 at least 25, 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.

Description

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.

Leaves without stipules; simple or pinnately or ternately compound. The family is characterized by opposite leaves. Alternate or whorled arrangements are rarely observed, with some Jasminum species presenting a spiral configuration. He did not designate what we now know as plant families, but placed his genera in artificial groups for purposes of identification. After the work of Linnaeus, names for groups that included the genera of Oleaceae were used, but none of them was a valid publication of the family name Oleaceae. For example, Antoine Laurent de Jussieu, in his Genera Plantarum in 1789, placed them in an order which he called "Jasmineae". In 1809, in a flora of Portugal, Johann Centurius Hoffmannsegg and Johann H.F. Link described at the taxonomic rank of family a group which they called "Oleinae". Their description is now regarded as the establishment of what we now know as Oleaceae.

The last revision of Oleaceae was published in 2004 in a series entitled The Families and Genera of Vascular Plants. Since that time, molecular phylogenetic work has shown that the next revision of Oleaceae must include substantial changes to the circumscription of genera.

Classification

Oleaceae is most closely related to the small Indo-Malesian family Carlemanniaceae. These two families form the second most basal clade in the order Lamiales, after Plocospermataceae. The families Plocospermataceae, Carlemanniaceae, Oleaceae, and Tetrachondraceae form a polyphyletic group known as the "basal Lamiales", which is in contrast to the monophyletic "core Lamiales".

Also, the family is notorious for incongruence between phylogenies based on plastid and nuclear DNA. The most likely cause of this incongruence is reticulate evolution resulting from rampant hybridization.

The delimitation of genera in Oleaceae has always been especially problematic. Some recent studies of small groups of related genera have shown that some of the genera are not monophyletic. For example, Olea section Tetrapilus is separate from the rest of Olea. It is a distinct group of 23 species and had been named as a genus, Tetrapilus, by João de Loureiro in 1790.

The genus Ligustrum has long been suspected of having originated from within Syringa, and this was confirmed in a cladistic comparison of selected chloroplast genes.

Osmanthus consists of at least three lineages whose closest relatives are not other lineages of Osmanthus.

Chionanthus is highly polyphyletic, with its species scattered across the phylogenetic tree of the subtribe Oleinae. Its African species are closer to Noronhia than to its type species, the North American Chionanthus virginicus. Its Madagascan species are phylogenetically within Noronhia and will be formally transferred to it in a forthcoming paper.