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The families of flowering plants

L. Watson and M.J. Dallwitz

Oleaceae Hoffmgg. & Link

Including Bolivariaceae Griseb., Forstiereae (Forstieraceae) Endl., Fraxineae (Fraxinaceae) S.F. Gray, Iasmineae (Iasminaceae) Link, Jasmineae (Jasminaceae) Juss., Lilacaceae Ventenat, Nyctantheae (Nyctanthaceae) J.G. Agardh, Syringaceae Horan.

Habit and leaf form. Trees and shrubs, or lianas (sometimes). Plants green and photosynthesizing. Self supporting, or climbing; the climbers stem twiners, or scrambling; Jasminum twining anticlockwise. Leptocaul. Mesophytic. Leaves deciduous (often), or persistent; opposite (nearly always), or alternate; in Jasminum, spiral; petiolate; non-sheathing; simple, or compound; when compound ternate, or pinnate. Lamina when simple dissected, or entire; pinnately veined; cross-venulate. Leaves exstipulate. Lamina margins entire, or serrate, or dentate. Vegetative buds scaly. Leaf development not ‘graminaceous’. Domatia occurring in the family (recorded in numerous species representing 6 genera); manifested as pits, or pockets, or hair tufts.

Leaf anatomy. The leaf lamina dorsiventral. Stomata mainly confined to one surface (being mostly or exclusively abaxial); usually anomocytic. Hairs present (consisting for the most part of peltate trichomes, which are sometimes flandular and may appear as transparent or sunken dots in the leaves); eglandular, or glandular. Complex hairs present; usually peltate (each comprising a unicellular stalk and an apical shield with exclusively vertical divisions). Adaxial hypodermis present (rarely), or absent. Cystoliths present (in Nyctanthes?), or absent. The mesophyll with sclerenchymatous idioblasts (often), or without sclerenchymatous idioblasts; containing crystals. The crystals solitary-prismatic (these small and acicular, in epidermis and/or mesophyll). Minor leaf veins without phloem transfer cells (7 genera).

Axial (stem, wood) anatomy. Pith homogeneous, or heterogeneous. Secretory cavities absent. Cork cambium present; initially deep-seated (rarely), or initially superficial. Nodes unilacunar. Primary vascular tissues in a cylinder, without separate bundles; collateral. Internal phloem absent. Cortical bundles present (very rarely?), or absent. Medullary bundles absent. Secondary thickening developing from a conventional cambial ring. Primary medullary rays narrow.

The wood ring porous to diffuse porous. The vessels small (typically, sometimes extremely so), or medium (in Linociera); variously solitary to radially paired, or in radial multiples, or clustered, or in tangential arcs. The vessel end-walls scalariform (usually), or scalariform and simple (a few cross bars occasionally seen). The vessels with vestured pits, or without vestured pits; with spiral thickening. The axial xylem with tracheids, or without tracheids; with vasicentric tracheids (in several genera), or without vasicentric tracheids; with fibre tracheids (in several genera), or without fibre tracheids; with libriform fibres (commonly), or without libriform fibres; at least sometimes including septate fibres, or without septate fibres (?). The fibres with spiral thickening, or without spiral thickening. The parenchyma paratracheal (typically), or apotracheal (occasionally diffuse, or absent). ‘Included’ phloem absent. The wood not storied. Tyloses present, or absent.

Reproductive type, pollination. Plants hermaphrodite (usually), or polygamomonoecious.

Inflorescence, floral, fruit and seed morphology. Flowers solitary, or aggregated in ‘inflorescences’; when aggregated, in racemes, or in fascicles, or in panicles. The ultimate inflorescence units cymose. Flowers bracteate, or ebracteate; often fragrant; regular; usually 2–6 merous; tricyclic, or tetracyclic. Free hypanthium absent. Hypogynous disk present (around G), or absent; intrastaminal.

Perianth with distinct calyx and corolla (usually), or sepaline (the corolla sometimes lacking); typically 8; 2 whorled (usually), or 1 whorled; isomerous. Calyx 4(–15); 1 whorled; gamosepalous; entire, or lobulate, or blunt-lobed, or toothed (sometimes obsolete); regular; valvate. Corolla when present (i.e. usually) 4(–12); 1 whorled; polypetalous (rarely, more or less), or gamopetalous; imbricate, or valvate (or induplicate-valvate), or contorted; regular.

Androecium 2 (usually), or 4 (rarely). Androecial members adnate (to the corolla), or free of the perianth; free of one another; 1 whorled. Androecium exclusively of fertile stamens. Stamens 2(–4); reduced in number relative to the adjacent perianth; oppositisepalous; filantherous, or with sessile anthers. Anthers dorsifixed, or basifixed; dehiscing via longitudinal slits; introrse. Endothecium developing fibrous thickenings. Microsporogenesis simultaneous. The initial microspore tetrads tetrahedral, or isobilateral, or T-shaped, or linear. Anther wall initially with one middle layer, or initially with more than one middle layer. Tapetum glandular. Pollen grains aperturate; (2–)3(–4) aperturate; colpate, or colporate (colporoidate, occasionally rupate); 2-celled (in 6 genera), or 3-celled (in Fontanesia).

Gynoecium 2 carpelled. Carpels reduced in number relative to the perianth. The pistil 2 celled. Gynoecium syncarpous; synovarious to eu-syncarpous; superior. Ovary 2 locular. Gynoecium median, or transverse, or oblique; stylate. Styles 1; apical. Stigmas 2 lobed; dry type; papillate, or non-papillate; Group II type. Placentation axile. Ovules (1–)2(–50) per locule (usually two, but Jasminoideae with 1, 4 or ‘many’); pendulous, or ascending; with dorsal raphe; usually collateral; non-arillate; anatropous, or amphitropous; unitegmic; tenuinucellate. Endothelium differentiated. Embryo-sac development Polygonum-type, or Allium-type. Polar nuclei fusing prior to fertilization. Antipodal cells formed; 3; not proliferating; ephemeral. Synergids hooked. Endosperm formation cellular. Embryogeny caryophyllad, or solanad (?).

Fruit fleshy, or non-fleshy; dehiscent, or indehiscent, or a schizocarp. Mericarps when schizocarpic, 2; samaroid. Fruit when non-schizocarpic, a capsule, or a berry, or a drupe. Capsules loculicidal. Fruit 1–4 seeded. Seeds endospermic, or non-endospermic. Endosperm oily. Embryo rudimentary at the time of seed release (in Fraxinus excelsior), or weakly differentiated to well differentiated (?). Cotyledons 2. Embryo achlorophyllous (5/12); straight.

Seedling. Germination phanerocotylar, or cryptocotylar.

Physiology, phytochemistry. C3. C3 physiology recorded directly in Ligustrum, Syringa. Sugars transported as oligosaccharides + sucrose, or as sugar alcohols + oligosaccharides + sucrose (and sucrose nowhere predominating, in the 6 genera sampled). Not cyanogenic. Alkaloids present (commonly), or absent. Verbascosides detected (4 genera). Cornoside detected (Forsythia). Arbutin absent. Iridoids detected; ‘Route I’ type (normal and seco). Saponins/sapogenins present, or absent. Proanthocyanidins absent. Flavonols present, or absent; quercetin, or kaempferol and quercetin. Ellagic acid absent (8 genera, species). Ursolic acid present. Aluminium accumulation not found.

Special distinguishing feature. The funicles not as in Acanthaceae.

Geography, cytology. Temperate to tropical. Cosmopolitan, save in frigid regions. X = 10, 11, 13, 14, 23, 24.

Taxonomy. Subclass Dicotyledonae; Tenuinucelli. Dahlgren’s Superorder Gentianiflorae; Oleales. Cronquist’s Subclass Asteridae; Solanales. APG III core angiosperms; core eudicot; Superorder Asteranae; lamiid. APG IV Order Lamiales.

Species 900. Genera about 25; Abeliophyllum, Chionanthus, Comoranthus, Fontanesia, Forestiera, Forsythia, Fraxinus, Haenianthus, Hesperelaea, Jasminum, Ligustrum, Linociera, Menodora, Myxopyrum, Nestegis, Noronhia, Noronhia, Notelaea, Nyctanthes, Olea, Osmanthus, Phyllyrea, Picconia, Schrebera, Syringa Tessarandra.

General remarks. See Johnson 1957.

Economic uses, etc. Edible fruit and edible and medicinal ‘olive oil’ from Olea europaea, cultivated trees and shrubs, timber trees (Jasminum, Osmanthus, Forsythia, Syringa, Ligustrum, Fraxinus, etc.


O let me twine
Mine arms about that body, where against
My grainèd ash a thousand times hath broke
(‘Corialanus’, iv., 5)

If you will know my house,
’Tis at the tuft of olives here hard by
(‘As You Like It’, iii., 5 - in England, poet’s licence?)

Life (priest and poet say) is but a dream;
I wish no happier one than to be laid
Beneath a cool syringa’s scented shade
(Walter Savage Landor, ‘The Dragonfly’)

The lighter ash but half obstructs the view
Leaving grey openings where the light looks through
(John Clare, fragment before 1856 — Fraxinus excelsior, contrasted with elm q.v.)

O were my love yon lilac fair,
Wi’ purple blossoms to the spring
(Robert Burns)

Illustrations. • Le Maout and Decaisne: Jasminum. • Le Maout and Decaisne: Syringa. • Le Maout and Decaisne: Fraxinus, Olea. • Le Maout and Decaisne: Schrebera. • Ligustrum vulgare, Notelaea ovata: Lindley. • Fraxinus excelsior (B. Ent.). • Fraxinus exelsior: Eng. Bot. 902 (1866). • Fraxinus exelsior (simple-leaved form, as F. exelsior heterophylla): Eng. Bot. 903 (1866). • Fraxinus sieboldiana, as F. mariesii: Bot. Mag. 109 (1883). • Jasminum glaucum: Bot. Reg. 2013, 1837. • Jasminum officinale: Bot. Mag. 31, 1787. • Jasminum humile f. wallichianum: Bot. Reg. 1409, 1831. • Ligustrum vulgare (B. Ent.). • Ligustrum vulgare: Eng. Bot. 904 (1866). • Chionanthus broomeanus, as Noronhia: Hook. Ic. Pl. 14 (1880–82). • Olea dioica: R. Wight 2 (1850). • cf. Osmanthus decorus, as Phyllyrea vilmoriniana: Bot. Mag. 111 (1885). • Nestegis montana (as Olea): Hooker, Fl. Novae-Zelandiae (1853). • Leaf hairs of Forestiera, Jasminum, Lonicera and Olea (with leaf TS): Solereder, 1908.

We advise against extracting comparative information from the descriptions. This is much more easily achieved using the DELTA data files or the interactive key, which allows access to the character list, illustrations, full and partial descriptions, diagnostic descriptions, differences and similarities between taxa, lists of taxa exhibiting or lacking specified attributes, distributions of character states within any set of taxa, geographical distribution, genera included in each family, and classifications (Dahlgren; Dahlgren, Clifford, and Yeo; Cronquist; APG). See also Guidelines for using data taken from Web publications.

Cite this publication as: ‘Watson, L., and Dallwitz, M.J. 1992 onwards. The families of flowering plants: descriptions, illustrations, identification, and information retrieval. Version: 5th March 2018.’.