| | The Families of Angiosperms |
~ 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. Leaf development not ‘graminaceous’.
Leaf anatomy. The leaf lamina dorsiventral to centric. Mucilaginous epidermis present, or absent. Stomata mainly confined to one surface (the lower); paracytic. The mesophyll with sclerenchymatous idioblasts (commonly), or without sclerenchymatous idioblasts; containing crystals. The crystals solitary-prismatic.
Axial (stem, wood) anatomy. Cork cambium present; initially superficial. Nodes unilacunar. Primary vascular tissues in a cylinder, without separate bundles; collateral. Internal phloem absent. Cortical bundles present (in young stems). Medullary bundles absent. Secondary thickening developing from a conventional cambial ring. Primary medullary rays narrow.
The wood diffuse porous. The vessels small to medium; solitary, or radially paired, or in radial multiples (in most species, often of four or more cells), or in tangential arcs. The vessel end-walls simple. The vessels without vestured pits; without spiral thickening. The axial xylem with tracheids; with fibre tracheids, or without fibre tracheids; with libriform fibres, or without libriform fibres; without septate fibres. The fibres without spiral thickening. The parenchyma predominantly paratracheal. The secondary phloem stratified into hard (fibrous) and soft (parenchymatous) zones, or not stratified. ‘Included’ phloem absent. The wood not storied. Tyloses present.
Reproductive type, pollination. Unisexual flowers present, or absent. 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; variously depicted as all equal, or markedly unequal (then alternating long and short, the longer stamens opposite the petals); coherent (united into a tube at their bases); 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, phytochemistry. Not cyanogenic. Alkaloids present. Iridoids not detected. Saponins/sapogenins present, or absent. Proanthocyanidins present; cyanidin. Flavonols present; kaempferol and quercetin. Ellagic acid absent (Erythroxylum). 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 III core angiosperms; core eudicot; Superorder Rosanae; fabid. APG IV Order Malpighiales.
Species 250. Genera 4; Aneulophus, Erythroxylum, Nectaropetalum, Pinacopodium.
Economic uses, etc. Cocaine is extracted from the leaves of coca (Erythroxylum coca).
Illustrations. • Le Maout and Decaisne: Erythroxylum. • Erythroxylum coca: Bot. Mag. 120 (1894). • Erythroxylum coca: Köhler's Medizinal Pflanzen 1 (1887). • Erythroxylum pictum: Thonner. • Erythroxylum sp.: Lindley. • cf. Erythroxylum monogynum (as Sethia indica): R. Wight (1840). • Nectaropetalum capense, as Peglera: Hook. Ic. Pl. 29 (1907).
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: 25th April 2024. delta-intkey.com’.
