The following 29 extant genera are recognized in the family Oleaceae.[6]Linociera is not included, even though some authors continue to recognize it.Linociera is not easy to distinguish fromChionanthus, mostly because the latter ispolyphyletic and not clearly defined.
Thetype genus for Oleaceae isOlea, the olives. Recentclassifications recognize nosubfamilies, but the family is divided into fivetribes.[2] The distinctiveness of each tribe has been strongly supported inmolecular phylogenetic studies, but the relationships among the tribes were not clarified until 2014.[7] Thephylogenetic tree for Oleaceae is a 5-grade that can be represented as {Myxopyreae [Forsythieae (Fontanesieae <Jasmineae + Oleeae>)]}.
The majorcenters of diversity for Oleaceae are in Southeast Asia and Australia.[8] There are also a significant number of species in Africa, China,[9] and North America. In thetropics the family is represented in a variety ofhabitats, from low-lyingdry forest tomontanecloud forest. In Oleaceae, theseed dispersal is almost entirely bywind oranimals. In the case that the fruit is a berry, the species is mostly dispersed bybirds. The wind-dispersed fruits aresamaras.
Some of the older works have recognized as many as 29 genera in Oleaceae.[10] 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 genusJasminum in which as few as 200[11] or as many as 450[12] species have been accepted.
In spite of the sparsity of thefossil record, and the inaccuracy ofmolecular-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 berelictual 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 arewoody plants, mostlytrees andshrubs; a few arelianas. Some of the shrubs arescandent, climbing by scrambling into other vegetation.
Leaves withoutstipules;simple orpinnately orternatelycompound. The family is characterized by opposite leaves. Alternate or whorled arrangements are rarely observed, with someJasminum species presenting a spiral configuration.[11] Thelaminas are pinnately veined and can be serrate, dentate or entire at the margin.Domatia are observed in certain taxa. The leaves may be either deciduous or evergreen, with evergreen species predominating in warmtemperate andtropical regions, and deciduous species predominating in colder regions.
Theflowers are most often bisexual and actinomorphic, occurring inracemes orpanicles, and often fragrant. Thecalyx andcorolla, when present, are gamosepalous and gamopetalous, respectively, their lobes connate, at least at the base. Theandroecium has 2stamens. These are inserted on the corolla tube and alternate with the corolla lobes. Thestigmas are two-lobed. Thegynoecium consists of a compoundpistil with twocarpels. Theovary issuperior with twolocules. Theplacentation is axile.Ovules usually 2 per locule; sometimes 4, rarely many. Nectary disk, when present, encircling the base of the ovary. The plants are most oftenhermaphrodite but sometimes polygamomonoecious.
The obvious feature that distinguishes Oleaceae and its sister family,Carlemanniaceae, from all others, is the fact that while the flowers are actinomorphic, the number of stamens is reduced to two.
Carl Linnaeus named eight of the genera of Oleaceae in 1753 in hisSpecies Plantarum.[13] 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 avalid publication of the family name Oleaceae. For example,Antoine Laurent de Jussieu, in hisGenera Plantarum in 1789, placed them in an order which he called "Jasmineae".[14] In 1809, in a flora of Portugal,Johann Centurius Hoffmannsegg andJohann H.F. Link described at the taxonomic rank of family a group which they called "Oleinae".[15][16] Their description is now regarded as the establishment of what we now know as Oleaceae.[17]
The last revision of Oleaceae was published in 2004 in a series entitledThe 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 thecircumscription of genera.
Oleaceae is one of only a few major plant families for which no well-sampled molecular phylogenetic study has ever been conducted. The onlyDNA sequence study of the entire family sampled 76 species for two noncodingchloroplast loci,rps16 andtrnL–F. Little was determined in this study, largely because themutation rate in thechloroplast genome of Oleaceae is very low compared to that of most other angiosperm families.[19]
Also, the family is notorious for incongruence between phylogenies based on plastid andnuclear DNA. The most likely cause of this incongruence isreticulate evolution resulting from rampanthybridization.[20]
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,OleasectionTetrapilus is separate from the rest ofOlea. It is a distinct group of 23 species and had been named as a genus,Tetrapilus, byJoão de Loureiro in 1790.[21]
The genusLigustrum has long been suspected of having originated from withinSyringa, and this was confirmed in a cladistic comparison of selected chloroplast genes.[22]
Osmanthus consists of at least three lineages whose closest relatives are not other lineages ofOsmanthus.[23]
Chionanthus is highly polyphyletic, with its species scattered across the phylogenetic tree of the subtribe Oleinae. Its African species are closer toNoronhia than to itstype species, the North AmericanChionanthus virginicus. Its Madagascan species are phylogenetically withinNoronhia and will be formally transferred to it in a forthcoming paper.[20]
The monophyly ofNestegis is in considerable doubt, but few of its closest relatives have been sampled in phylogenetic studies.
^abPeter S. Green. 2004. "Oleaceae". pages 296-306. In: Klaus Kubitzki (editor) and Joachim W. Kadereit (volume editor).The Families and Genera of Vascular Plants volume VII. Springer-Verlag: Berlin; Heidelberg, Germany.ISBN978-3-540-40593-1
^Vernon H. Heywood, Richard K. Brummitt, Ole Seberg, and Alastair Culham.Flowering Plant Families of the World. Firefly Books: Ontario, Canada.ISBN978-1-55407-206-4.
^Anthony Huxley, Mark Griffiths, and Margot Levy (1992).The New Royal Horticultural Society Dictionary of Gardening. The Macmillan Press,Limited: London. The Stockton Press: New York.ISBN978-0-333-47494-5 (set).
^abRefulio-Rodriguez, Nancy F.; Olmstead, Richard G. (2014). "Phylogeny of Lamiidae".American Journal of Botany.101 (2):287–299.doi:10.3732/ajb.1300394.PMID24509797.
^Mei-chen Chang, Lien-ching Chiu, Zhi Wei, and Peter S. Green. 1996. "Oleaceae" pages 272-319. In: Wu Zhengyi, Peter H. Raven, and Hong Deyuan (editors). 1994 onward.Flora of China vol. 15: Myrsinaceae – Loganiaceae. Science Press: Beijing, China; and Missouri Botanical Garden Press: St. Louis, MO, USA.ISBN978-0-915279-37-1(vol. 15)ISBN978-0-915279-34-0 (set).
^Carolus Linnaeus (Carl von Linné). 1753.Species Plantarum, 1st edition, vol. 1,pages 6-9. Holmiae: Impensis Laurentii Salvii (Lars Salvius). (A facsimile with an introduction by William T. Stearn was published by the Ray Society in 1957).
^Antoine Laurent de Jussieu. 1789. "ORDO IV Jasmineae" pages 104-106. In:Genera plantarum :secundum ordines naturales disposita, ....
^Wallander, Eva; Albert, Victor A. (2000). "Phylogeny and classification of Oleaceae based onrps16 andtrnL-F sequence data".American Journal of Botany.87 (12):1827–41.doi:10.2307/2656836.JSTOR2656836.PMID11118421.
^abHong-Wa, Cynthia; Besnard, Guillaume (2013). "Intricate patterns of phylogenetic relationships in the olive family as inferred from multi-locus plastid and nuclear DNA sequence analyses: a close-up onChionanthus andNoronhia (Oleaceae)"".Molecular Phylogenetics and Evolution.67 (2):367–378.Bibcode:2013MolPE..67..367H.doi:10.1016/j.ympev.2013.02.003.PMID23415987.
^Li, Jianhua; Goldman-Huertas, Benjamin; DeYoung, Jeffrey; Alexander III, John (2012). "Phylogenetics and Diversification ofSyringa Inferred from Nuclear and Plastid DNA Sequences".Castanea.77 (1):82–88.doi:10.2179/11-016.S2CID83590628.
^Guo, Shi-Quan; Xiong, Min; Ji, Chun-Feng; Zhang, Zhi-Rong; Li, De-Zhu; Zhang, Zhi-Yong (2011). "Molecular phylogenetic reconstruction ofOsmanthus Lour. (Oleaceae) and related genera based on three chloroplast intergenic spacers".Plant Systematics and Evolution.294 (1–2):57–64.Bibcode:2011PSyEv.294...57G.doi:10.1007/s00606-011-0445-z.S2CID21252789.
