Family Erythroxylaceae
Erythroxylaceae Kunth~ Linaceae Including Nectaropetalaceae (Winkler) Exell & Mondonca Habit and leaf form. Trees and shrubs. Leaves well developed (sometimes accompanied by scale leaves). Mesophytic. Leaves alternate, or opposite (rarely); usually spiral; often persistently twice folded (longitudinally); ‘herbaceous’, or ‘herbaceous’ and membranous (the branches often covered with rudimentary leaves in the form of distichous scales); petiolate; non-sheathing; simple. Lamina entire; pinnately veined. Leaves stipulate. Stipules interpetiolar (rarely), or intrapetiolar; often caducous. Lamina margins entire. Leaves without a persistent basal meristem. Leaf anatomy. Mucilaginous epidermis present, or absent. Lamina dorsiventral to centric. The mesophyll with sclerencymatous idioblasts, or without sclerenchymatous idioblasts. Stem anatomy. Cork cambium present; initially superficial. Nodes unilacunar. Primary vascular tissue in a cylinder, without separate bundles. Cortical bundles present (in young stems). Medullary bundles absent. Internal phloem absent. Secondary thickening developing from a conventional cambial ring. The secondary phloem stratified into hard (fibrous) and soft (parenchymatous) zones, or not stratified. ‘Included’ phloem absent. Xylem with fibre tracheids. Vessel end-walls simple. Vessels without vestured pits. Reproductive type, pollination. Plants hermaphrodite, or dioecious (rarely); usually heterostylous. Inflorescence, floral, fruit and seed morphology. Flowers solitary, or aggregated in ‘inflorescences’; when solitary, axillary; when aggregated, in fascicles. Inflorescences axillary. Flowers small; regular; 5 merous; cyclic; pentacyclic. Free hypanthium absent. Hypogynous disk absent. Perianth with distinct calyx and corolla; 10; 2 whorled; isomerous. Calyx 5; 1 whorled; polysepalous, or gamosepalous; regular; persistent; imbricate (quincuncial), or valvate. Corolla 5; 1 whorled; appendiculate (the petals usually internally ligulate), or not appendiculate; polypetalous, or partially gamopetalous; imbricate, or contorted; regular. Androecium 10. Androecial members free of the perianth; all equal; coherent (united into a tube at the base); 1 adelphous; 1 whorled. Androecium exclusively of fertile stamens. Stamens 10; diplostemonous; both alternating with and opposite the corolla members. Anthers dorsifixed; versatile; dehiscing via longitudinal slits; introrse; tetrasporangiate. Endothecium developing fibrous thickenings. Anther epidermis persistent. Microsporogenesis simultaneous. The initial microspore tetrads tetrahedral and decussate. Anther wall initially with one middle layer, or initially with more than one middle layer. Tapetum glandular. Pollen grains aperturate; 3 aperturate; colporate (almost zonorate); 3-celled. Gynoecium 3 carpelled. Carpels reduced in number relative to the perianth. The pistil (2–)3 celled. Gynoecium syncarpous; synovarious to synstylovarious; superior. Ovary (2–)3 locular (usually only one fertile). Gynoecium stylate. Styles (2–)3; free to partially joined; apical. Stigmas dry type; papillate; Group II type. Placentation axile, or apical. Ovules 1 per locule; funicled; pendulous; epitropous (Engler); non-arillate; anatropous, or hemianatropous; bitegmic; crassinucellate. Outer integument not contributing to the micropyle. Endothelium differentiated. Embryo-sac development Polygonum-type. Polar nuclei fusing prior to fertilization. Antipodal cells formed; 3; not proliferating; ephemeral. Synergids with filiform apparatus. Endosperm formation nuclear. Embryogeny solanad. Fruit fleshy; indehiscent; a drupe. The drupes with one stone (one-loculed). Fruit 1 seeded. Seeds endospermic, or non-endospermic (rarely). Endosperm not oily (starchy). Seeds with starch. Cotyledons 2; flat. Embryo chlorophyllous (1/1); straight. Seedling. Germination phanerocotylar. Physiology, biochemistry. Not cyanogenic. Alkaloids present. Iridoids not detected. Proanthocyanidins present; cyanidin. Flavonols present; kaempferol and quercetin. Ellagic acid absent (Erythroxylum). Saponins/sapogenins present, or absent. Aluminium accumulation not found. Geography, cytology. Sub-tropical to tropical. Pantropical. X = 12. Taxonomy. Subclass Dicotyledonae; Crassinucelli. Dahlgren’s Superorder Rutiflorae; Geraniales. Cronquist’s Subclass Rosidae; Linales. APG 3 core angiosperms; core eudicot; Superorder Rosanae; fabid; Order Malpighiales. Species 250. Genera 4; Aneulophus, Erythroxylum, Nectaropetalum, Pinacopodium. Economic uses, etc. Cocaine is extracted from the leaves of coca (Erythroxylum coca). Illustrations. |
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