Opiliaceae Valeton
Including Cansjeraceae J.G. Agardh
Habit and leaf form. Trees and shrubs, or lianas. Partially parasitic. On roots of the host. Self supporting, or climbing. Mesophytic. Leaves alternate; non-sheathing; simple. Lamina entire (turning a characteristic yellow-green on drying); pinnately veined; cross-venulate. Leaves exstipulate.
Leaf anatomy. Stomata paracytic.
Lamina dorsiventral (usually), or centric. Cystoliths commonly present. The mesophyll containing mucilage cells, or not containing mucilage cells; without calcium oxalate crystals.
Stem anatomy. Cork cambium present; initially superficial. Cortical bundles absent. Medullary bundles absent. Internal phloem absent. Secondary thickening developing from a conventional cambial ring. ‘Included’ phloem absent. Xylem with tracheids, or without tracheids (Lepionurus); with fibre tracheids, or without fibre tracheids. Vessel end-walls simple. Wood parenchyma apotracheal (diffuse).
Reproductive type, pollination. Plants hermaphrodite, or dioecious (infrequently).
Inflorescence, floral, fruit and seed morphology. Flowers aggregated in ‘inflorescences’; in racemes, in panicles, in spikes, and in umbels. Inflorescences axillary, or cauliflorous. Flowers small; fragrant (at least sometimes), or odourless; regular; 4 merous, or 5 merous; cyclic; tetracyclic. Free hypanthium absent. Hypogynous disk present; of separate members (alternating with the stamens).
Perianth with distinct calyx and corolla, or sepaline (the corolla usually absent in female flowers); 4–5 (female flowers), or 8, or 10; 1 whorled (female flowers), or 2 whorled; isomerous. Calyx 4, or 5; 1 whorled; gamosepalous; lobulate (the lobes sometimes almost obsolete), or blunt-lobed; cupuliform; regular; persistent; non-accrescent; open in bud. Corolla 4, or 5; 1 whorled; polypetalous, or gamopetalous (sometimes basally connate). Corolla lobes markedly longer than the tube. Corolla valvate; regular.
Androecium 4, or 5. Androecial members free of the perianth, or adnate (to the corolla); free of one another; 1 whorled. Androecium exclusively of fertile stamens. Stamens 4, or 5; isomerous with the perianth; nearly always alternisepalous. Anthers dehiscing via longitudinal slits; tetrasporangiate. Endothecium developing fibrous thickenings. Anther epidermis persistent. Microsporogenesis simultaneous. The initial microspore tetrads tetrahedral. Anther wall initially with one middle layer, or initially with more than one middle layer; of the ‘dicot’ type. Tapetum glandular. Pollen grains aperturate; 3 aperturate; colporate (to colporoidate); 2-celled.
Gynoecium 2–5 carpelled. Carpels reduced in number relative to the perianth to isomerous with the perianth. The pistil 1 celled. Gynoecium syncarpous; eu-syncarpous; superior to partly inferior (sometimes half immersed in the disk). Ovary 1 locular. Gynoecium non-stylate, or stylate. Styles attenuate from the ovary; apical; when present, shorter than the ovary. Stigmas 1; sometimes capitate. Placentation basal, or free central. Ovules in the single cavity 1; pendulous (usually), or ascending (rarely, when basal); non-arillate; anatropous; without integuments, or unitegmic; tenuinucellate. Embryo-sac development Polygonum-type. Polar nuclei fusing prior to fertilization. Antipodal cells formed; 3; not proliferating; ephemeral. Synergids hooked (with filiform apparatus). Endosperm formation cellular. Endosperm haustoria present; chalazal.
Fruit fleshy; indehiscent; a drupe. The drupes with one stone. Fruit 1 seeded. Seeds endospermic. Endosperm oily. Seeds without a testa. Embryo well differentiated (though rather small). Cotyledons (2–)3, or 4. Testa lacking.
Seedling. Germination cryptocotylar.
Physiology, biochemistry. Saponins/sapogenins absent.
Geography, cytology. Tropical. Pantropical. X = 10.
Taxonomy. Subclass Dicotyledonae; Crassinucelli. Dahlgren’s Superorder Myrtiflorae; Myrtales. Cronquist’s Subclass Rosidae; Santalales. APG (1998) Eudicot; core Eudicot; neither Rosid nor Asterid; Santalales. Species 28. Genera 10; Agonandra, Cansjera, Champereia, Gjellerupia, Lepionurus, Melientha, Opilia, Pentarhopalopilia, Rhopalopilia, Urobotrya.
Illustrations. • Technical details (Opilia).
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).
