Family Strychnaceae
Strychnaceae Link.~ Loganiaceae Excluding Antoniaceae Habit and leaf form. Trees (to 40 m), or shrubs, or lianas; non-laticiferous and without coloured juice. Self supporting, or climbing; the climbers tendril climbers, or scrambling (spiny or prickly). Mesophytic, or xerophytic. Leaves opposite, or whorled; when whorled, 3 per whorl; ‘herbaceous’, or leathery (commonly, in Strychnos); petiolate, or subsessile; connate, or not connate; simple. Lamina entire; pinnately veined, or palmately veined; cross-venulate. Leaves stipulate, or exstipulate (in Strychnos often represented only by an interpetiolar ridge). Stipules interpetiolar, or intrapetiolar; free of one another, or concrescent (Strychnos sect. Spinosae exhibiting ‘normal’, free stipules); ochreate (Neubergia), or not ochreate; with colleters. Leaves without a persistent basal meristem. Domatia occurring in the family; manifested as pockets, or hair tufts. Leaf anatomy. Hairs present, or absent; eglandular. Complex hairs absent. The mesophyll with sclerencymatous idioblasts. Minor leaf veins without phloem transfer cells (Strychnos). Stem anatomy. Internal phloem present. Secondary thickening anomalous; from a single cambial ring. ‘Included’ phloem present. Xylem commonly with tracheids; with fibre tracheids (usually), or without fibre tracheids (e.g. in Sect. Spinosae); with libriform fibres, or without libriform fibres (fibres seemingly always non-septate). Vessel end-walls generally horizontal (or almost so), or horizontal to oblique (e.g., in Neuburgia); seemingly always simple. Vessels with vestured pits. Primary medullary rays mixed wide and narrow (uniseriate and multiseriate). Tile cells present (e.g. Neuburgia?), or absent. Wood ring porous, or diffuse porous; not storied; parenchyma usually present, apotracheal, or paratracheal, or apotracheal and paratracheal. Reproductive type, pollination. Fertile flowers hermaphrodite. Plants hermaphrodite; homostylous. Pollination entomophilous. Inflorescence, floral, fruit and seed morphology. Flowers aggregated in ‘inflorescences’ (usually), or solitary; in cymes, or in corymbs, or in panicles. The ultimate inflorescence unit cymose. Inflorescences cymes or corymbose-paniculate. Flowers bracteate (bracts small); regular; 4–5 merous; cyclic; tetracyclic. Free hypanthium absent. Hypogynous disk absent. Perianth with distinct calyx and corolla; 8, or 10; 2 whorled; isomerous. Calyx 4–5; 1 whorled; polysepalous, or gamosepalous; unequal but not bilabiate, or regular; imbricate. Epicalyx absent. Corolla 1–5; 1 whorled; gamopetalous (the tube short); valvate; regular; green, or white, or yellow, or orange (or membranous); fleshy. Androecium 4–5. Androecial members adnate; all equal; free of one another; 1 whorled. Androecium exclusively of fertile stamens. Stamens 4–5; inserted midway down the corolla tube, or in the throat of the corolla tube; isomerous with the perianth; oppositisepalous; alternating with the corolla members. Anthers separate from one another, or connivent (Gardneria); dorsifixed, or dorsifixed to basifixed (?); dehiscing via longitudinal slits; introrse; bilocular (usually), or four locular (some Gardneria species); appendaged (Neubergia), or unappendaged. The anther appendages when present, apical, or apical and basal. Microsporogenesis simultaneous. The initial microspore tetrads tetrahedral. Tapetum glandular. Pollen grains aperturate; (2–)3(–4) aperturate; colporate (rarely syncolpate); 3-celled. Gynoecium 2 carpelled. Carpels reduced in number relative to the perianth. The pistil 2 celled. Gynoecium syncarpous; eu-syncarpous; superior. Ovary 2 locular. Gynoecium median; stylate. Styles 1; attenuate from the ovary; apical. Stigmas 1 lobed, or 2 lobed; more or less capitate. Placentation axile. Ovules (1–)2–50 per locule (to ‘many’); non-arillate; anatropous; unitegmic; tenuinucellate. Endothelium not differentiated. Embryo-sac development Polygonum-type. Polar nuclei fusing prior to fertilization. Antipodal cells formed; 3; not proliferating; ephemeral. Synergids pear-shaped. Hypostase absent. Endosperm formation nuclear. Embryogeny onagrad. Fruit indehiscent; a berry, or a drupe (sometimes large). Seeds endospermic; wingless. Embryo straight. Physiology, biochemistry. Not cyanogenic. Alkaloids present. Iridoids detected; ‘Route I’ type (plus complex indole alkaloids). Proanthocyanidins absent. Ellagic acid absent. Saponins/sapogenins present, or absent. Aluminium accumulation demonstrated. Geography, cytology. Sub-tropical to tropical. Pantropical and subtropical. 2n = 44, 88, 110. Supposed basic chromosome number of family: 11. Ploidy levels recorded: 4, 8, and 10. Taxonomy. Subclass Dicotyledonae; Tenuinucelli. Dahlgren’s Superorder Gentianiflorae; Gentianales. Cronquist’s Subclass Asteridae; Gentianales. APG 3 core angiosperms; core eudicot; Superorder Asteranae; lamiid; Order Gentianales (as a synonym of Loganiaceae). Species 250. Genera 4; Strychnos, Scyphostrychnos, Gardneria, Neubergia. Leeuwenberg 1980, under Loganiaceae. Struwe et al. (1994) include Antoniaceae and Spigelia here, but the present descriptions suggest Strychnaceae are somewhat closer to Gentianaceae, Loganiaceae sensu stricto and Potaliaceae. See comments under Loganiaceae. Illustrations. |
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