Neotropical Oleaceae

Description

Trees, shrubs or sometimes climbers; unarmed. Leaves opposite, petiolate, commonly with swollen base, or sessile, simple, trifoliolate (Jasminum) or imparipinnate (Fraxinus, Jasminum), entire, dentate to obscurely crenulate, pilose domatia sometimes present in the axils of the primary veins and midrib, sometimes glandular in the abaxial side (Forestiera); stipules absent. Inflorescences terminal or axillary, cymose or racemose, rarely one-flowered. Flowers actinomorphic, bisexual or rarely unisexual (Forestiera, plants dioecious); calyx 4(-15)-toothed, fused with short tube or sepals rarely free, lobes valvate, or calyx absent (Fraxinus); corolla present or absent (Forestiera, some Fraxinus) to early caducous (Priogymnanthus), 4-lobed (except some Jasminum species), fused with short tube or tube absent, rarely tube long and corolla somewhat infundibuliform or hypocrateriform (Jasminum, Menodora, Schrebera), petals sometimes united in pairs at the bases of the stamen filaments, petals rarely free, lobes valvate or imbricate; androecium with 2(-4) stamens, free, epipetalous, attached to the corolla tube, anthers dehiscence longitudinally; gynoecium syncarpous, ovary superior, carpels 2, locules 2, ovules 1-2(-4) per locule, axillary, pendulous, style 1, stigma 2-lobed or capitate. Fruits drupes, berries (Jasminum), samaroids (Fraxinus) or capsules (Schrebera, Menodora). Seeds 1(-2); endosperm present or near absent.

Notes on delimitation

• Included in the Lamiales by the APGIII classification.

Distribution in the Neotropics

• Chionanthus L. - Mesoamerica, Caribbean.
• Forestiera Poir. - Mesoamerica, Caribbean, and Ecuador.
• Fraxinus L. - Mexico, Mesoamerica.
• Haenianthus Griseb. - Cuba, Hispaniola.
• Menodora Humb. & Bonpl. - Mexico, Southern Brazil, Bolivia, Paraguay, Argentina.
• Osmanthus Lour. - Mexico.
• Priogymnanthus P.S.Green - Ecuador, Brazil, Bolivia, Paraguay.
• Schrebera Roxb. - Peru (?).
• Jasminum L. - one species introduced as ornamental plant, now naturalized in South America and Caribbean.
• Ligustrum L. - two or three species introduced as street trees, now naturalized in Mexico, Brazil, and Argentina.

Distinguishing characters (always present)

• Leaves opposite.
• Corolla tetramerous and actinomorphic.

Other important characters

• Stamens 2.
• Ovules 2 per locule.
• Fruit 1-seeded drupes.

Key differences from similar families

• Leaves opposite and estipulate; flower with four petals and two stamens put this family beyond confusion with other Euasterids in the Lamiales.

Number of genera

• 10 genera: Chionanthus L., Forestiera Poir., Fraxinus L., Haenianthus Griseb., Jasminum L., Ligustrum L., Menodora Humb. & Bonpl., Osmanthus Lour., Priogymnanthus P.S.Green and Schrebera Roxb.

Useful tips for generic identification

• Leaves composite - Jasminum (trifoliolate or imparipinnate, corolla present, fruit a 2-lobed berry) and Fraxinus (imparipinnate, apetalous, except by F. cuspidata from Mexico (Fragrant ash), fruit winged).
• Leaves simple - Chionanthus (calyx and corolla present, petals valvate, drupes with hard endocarp).
• Forestiera (flowers unisexual, calyx vestigial or absent, corolla absent, drupes).
• Haenianthus (calyx and corolla present, petals valvate, peltate scales in the abaxial side of petals, drupes with thin endocarp).
• Ligustrum (calyx and corolla present, petals valvate, berries or drupes with thin endocarp).
• Menodora (calyx and corolla present, corolla lobes imbricate, capsules).
• Osmanthus (calyx and corolla present, petals imbricate, drupes with hard endocarp)., Priogymnanthus (calyx absent, corolla early caduceus, drupes), Schrebera (calyx campanulate, corolla infundibuliform to hypocrateriform, lobes imbricate, capsules).

Notable genera and distinguishing features

• Chionanthus - corolla lobes 4, united in pairs at bases and characteristically linear, sometimes shortly oblong.

Status

• Native (Chionanthus, Forestiera, Fraxinus, Haenianthus, Menodora, Priogymnanthus and Schrebera).
• Cultivated and naturalised (Jasminum and Ligustrum).

General notes

• Hesperelaea palmeri A.Gray, only species on the genus, was endemic of Guadalupe Island, Mexico, but is reported as extinct by introduced goats.

Important literature

APG III. 2009. An update of the Angiosperm Phylogeny Group classification for the orders and families of flowering plants. Botanical Journal of the Linnean Society 161(3): 105-121.

Cornejo, X. & Bonifaz, C. 2006. Forestiera ecuadorensis: Una nueva especie endémica de Oleaceae y un nuevo registro genérico para Ecuador. Brittonia 58: 78-82.

Green, P.S. 1994. A Revision of Chionanthus (Oleaceae) in S. America and the Description of Priogymnanthus, gen. nov. Kew Bull. 49: 261-286.

Green, P.S. 2004. Oleaceae. In: Kadereit, J.W. (ed.). The families and genera of Vascular Plants vol 7, pp. 296-306. Springer Verlag, Berlin.
Hammel, B.E. & Cornejo, X. 2009. Forestiera isabelae (Oleaceae), una especie nueva para Costa Rica. Novon 19: 52-55.

Steyermark, J.A. 1932. A revision of the genus Menodora. Ann. Missouri Bot. Gard. 19. 87-160: 162-176.

Wallander, E. 2008. Systematics of Fraxinus (Oleaceae) and evolution of dioecy. Plant Syst. Evol. 273: 25-49.

Wallander, E. & Albert, V.A. 2000. Phylogeny and classification of Oleaceae based on rps16 and trnL-F sequence data. Amer. J. Bot. 87: 213-231.

Zona, S. 1991. A morphometric and taxonomic reevaluation of Haenianthus (Oleaceae). Canad. J. Bot. 69: 489-493.

How to cite

Lombardi, J.A. (2010). Neotropical Oleaceae. In: Milliken, W., Klitgĺrd, B. & Baracat, A. (2009 onwards), Neotropikey - Interactive key and information resources for flowering plants of the Neotropics. http://www.kew.org/science/tropamerica/neotropikey/families/Oleaceae.htm.