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The families of flowering plants

L. Watson and M.J. Dallwitz

Opiliaceae Valeton

Including Cansjeraceae J.G. Agardh

Habit and leaf form. Trees and shrubs, or lianas. Plants parasitic; haustorially parasitic; green and photosynthesizing; 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. The leaf lamina dorsiventral (usually), or centric. Stomata mainly confined to one surface, or on both surfaces; at least sometimes paracytic. Hairs at least sometimes multicellular and branched. Cystoliths commonly present (and similar ones in the parenchyma of the axes). The mesophyll containing mucilage cells, or not containing mucilage cells; with sclerenchymatous idioblasts (these branched, in the mesophyll); without crystals.

Axial (stem, wood) anatomy. Cork cambium present; initially superficial. Primary vascular tissues in a cylinder, without separate bundles (?); collateral. Internal phloem absent. Cortical bundles absent. Medullary bundles absent. Secondary thickening developing from a conventional cambial ring.

The wood diffuse porous. The vessels moderately small; exclusively solitary, or solitary, radially paired, and in radial multiples (in Opilia). The vessel end-walls simple. The vessels without vestured pits; without spiral thickening. The axial xylem with tracheids, or without tracheids (Lepionurus); without vasicentric tracheids; with fibre tracheids, or without fibre tracheids; with libriform fibres, or without libriform fibres; including septate fibres, or without septate fibres. The fibres without spiral thickening. The parenchyma apotracheal (diffuse). The secondary phloem not stratified. ‘Included’ phloem absent. The wood not storied.

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, phytochemistry. Saponins/sapogenins absent. Aluminium accumulation suggested by the yellowing of dried leaves.

Geography, cytology. Tropical. Pantropical. X = 10.

Taxonomy. Subclass Dicotyledonae; Crassinucelli. Dahlgren’s Superorder Myrtiflorae; Myrtales. Cronquist’s Subclass Rosidae; Santalales. APG III core angiosperms; core eudicot; Superorder Santalanae. APG IV Order Santalales.

Species 28. Genera 10; Agonandra, Cansjera, Champereia, Gjellerupia, Lepionurus, Melientha, Opilia, Pentarhopalopilia, Rhopalopilia, Urobotrya.

Illustrations. • Opilia amentacea: R. Wight, Ic. Pl. Indiae Orient. 1 (1840). • Cansjera rheedei: R. Wight, Ic. Pl. Indiae Orient. 1 (1852). • Agonandra brasiliensis: Fl. Brasil. 12 (1872–77). • Opilia amentacea: Thonner. • Cansjera leptostachya (as timorensis): mesophyll cystoliths (Solereder, 1908). • Leaf hair of Cansjera parviflora, with hairs from Icacinaceae (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.’.