Olacaceae Juss.
Including Aptandraceae Miers, Cathedraceae Van Tiegh., Chaunochitaceae (Chaunochitonaceae) Van Tiegh., Coulaceae Van Tiegh. ex Solander, Harmandiaceae Van Tiegh., Heisteriaceae Van Tiegh., Schoepfiaceae Blume, Scorodocarpaceae Van Tiegh., Strombosiaceae Van Tiegh., Tetrastylidaceae Van Tieghem., Ximeniaceae Van Tiegh.
Excluding Octoknemaceae, Erythropalaceae
Habit and leaf form. Trees, shrubs, and lianas; laticiferous, or non-laticiferous and without coloured juice; resinous, or not resinous. Autotrophic, or partially parasitic. When parasitic, on roots of the host. Self supporting, or climbing. Mesophytic, or xerophytic. Leaves alternate; distichous (commonly), or spiral; leathery; petiolate; non-sheathing; gland-dotted, or not gland-dotted; aromatic, or without marked odour, or foetid; simple. Lamina entire; one-veined, or pinnately veined; cross-venulate. Leaves exstipulate. Lamina margins entire.
General anatomy. Plants with laticifers (articulated or non-articulated), or without laticifers.
Leaf anatomy. Lamina with secretory cavities (in Coulieae), or without secretory cavities. Secretory cavities containing resin; Secretory cavities schizogenous. The mesophyll with sclerencymatous idioblasts (spicular fibres), or without sclerenchymatous idioblasts.
Stem anatomy. Secretory cavities present (Coulieae), or absent; with resin. Cork cambium present; initially superficial. Nodes unilacunar, or tri-lacunar, or multilacunar (rarely). Internal phloem absent. Secondary thickening developing from a conventional cambial ring. Xylem with tracheids, or without tracheids; with fibre tracheids, or without fibre tracheids; with libriform fibres, or without libriform fibres. Vessel end-walls scalariform, or simple (usually). Wood parenchyma apotracheal (typically, exclusively), or paratracheal (Schoepfia).
Reproductive type, pollination. Plants hermaphrodite, or monoecious, or dioecious.
Inflorescence, floral, fruit and seed morphology. Flowers aggregated in ‘inflorescences’; in panicles, in racemes, and in heads. Inflorescences axillary. Flowers small; regular; cyclic. Free hypanthium present, or absent. Hypogynous disk present; annular.
Perianth with distinct calyx and corolla (but the calyx lobes reduced); 6–12; 2 whorled; isomerous. Calyx 3–6; 1 whorled; gamosepalous; entire, or lobulate, or blunt-lobed, or toothed; cupuliform; regular; fleshy, or non-fleshy; persistent; accrescent (often), or non-accrescent; imbricate, or open in bud. Corolla 3–6; 1 whorled; polypetalous, or gamopetalous (basally, rarely forming a long tube); valvate; regular; not fleshy.
Androecium 3–6, or 6–12, or 9–18. Androecial members unbranched; free of the perianth, or adnate (to the corolla); free of one another, or coherent; sometimes 1 adelphous (the filaments united basally); 1 whorled. Androecium exclusively of fertile stamens, or including staminodes. Stamens 3–18; reduced in number relative to the adjacent perianth to polystemonous; alternisepalous (when as many as C), or oppositisepalous; alternating with the corolla members, or opposite the corolla members, or both alternating with and opposite the corolla members (?). Anthers basifixed; versatile, or non-versatile; dehiscing via pores, or dehiscing via short slits, or dehiscing via longitudinal slits; tetrasporangiate. Endothecium developing fibrous thickenings. Anther epidermis persistent. Microsporogenesis simultaneous. The initial microspore tetrads tetrahedral, or isobilateral, or decussate. Anther wall initially with more than one middle layer. Tapetum glandular. Pollen grains aperturate; 3 aperturate, or 3–4(–5) aperturate, or 6–8 aperturate; colpate, or porate, or colporate, or foraminate; 2-celled, or 3-celled.
Gynoecium (2–)3(–5) carpelled. Carpels isomerous with the perianth, or reduced in number relative to the perianth. The pistil 1 celled, or (2–)3(–5) celled. Gynoecium syncarpous; synstylovarious, or eu-syncarpous; superior (usually), or partly inferior. Ovary (2–)3(–5) locular (basally— sometimes unilocular above), or 1 locular. Gynoecium stylate. Styles 1; apical. Stigmas 2–5 lobed. Placentation when unilocular, free central; when plurilocular, axile, or axile to apical. Ovules in the single cavity when unilocular, (2–)3(–5); 1 per locule; pendulous; anatropous; without integuments, or unitegmic, or bitegmic; tenuinucellate, or pseudocrassinucellate. Embryo-sac development Polygonum-type, or Allium-type. Polar nuclei fusing prior to fertilization. Antipodal cells formed; 1–3; not proliferating; ephemeral. Synergids hooked (with filiform apparatus). Endosperm formation cellular, or helobial. Endosperm haustoria present; chalazal.
Fruit fleshy, or non-fleshy; indehiscent; a drupe, or a nut; enclosed in the fleshy hypanthium, or enclosed in the fleshy perianth, or without fleshy investment. Seeds endospermic. Endosperm oily. Seeds with a testa. Cotyledons 2–6. Embryo chlorophyllous (1/2); straight.
Seedling. Germination phanerocotylar, or cryptocotylar.
Physiology, biochemistry. Cyanogenic, or not cyanogenic. Alkaloids present, or absent (mostly). Iridoids not detected. Saponins/sapogenins absent (usually). Aluminium accumulation not found (with Octoknema excluded).
Geography, cytology. Sub-tropical to tropical. Pantropical and subtropical. X = 19, 20.
Taxonomy. Subclass Dicotyledonae; Crassinucelli. Dahlgren’s Superorder Santaliflorae; Santalales. Cronquist’s Subclass Rosidae; Santalales. APG (1998) Eudicot; core Eudicot; neither Rosid nor Asterid; Santalales. Species 250. Genera 25; Anacolosa, Aptandra, Brachynema, Cathedra, Chaunochiton, Coula, Curupira, Diogoa, Douradoa, Dulacia, Harmandia, Heisteria, Malania, Minquartia, Ochanostachys, Olax, Ongokea, Phanerodiscus, Ptychopetalum, Schoepfia, Scorodocarpus, Strombosia, Strombosiopsis, Tetrastylidium, Ximenia.
Economic uses, etc. Edible fruit from Ximenia (false sandalwood, hog-plum).
Illustrations. • Technical details (Olax). • Technical details (Aptandra). • Technical details (Olax).
Cite this publication as: ‘L. Watson and M. J. Dallwitz (1992 onwards). The Families of Flowering Plants: Descriptions, Illustrations, Identification, and Information Retrieval. Version: 14th December 2000. http://biodiversity.uno.edu/delta/’. Dallwitz (1980), Dallwitz, Paine and Zurcher (1993, 1995, 2000), and Watson and Dallwitz (1991) should also be cited (see References).
