Family Ehretiaceae
Ehretiaceae Lindl.~ Boraginaceae Including Cordiaceae R.Br., Sebestanae (Sebestenaceae) Vent. Habit and leaf form. Trees, or shrubs, or herbs (rarely); non-laticiferous and without coloured juice. ‘Normal’ plants. Mesophytic. Leaves alternate (rarely sub-opposite); spiral; non-sheathing; simple. Lamina dissected (sometimes, in Cordia), or entire (usually); pinnately veined; cross-venulate. Leaves exstipulate. Lamina margins entire, or crenate, or serrate, or dentate. Leaves without a persistent basal meristem. Domatia occurring in the family (from Cordia and Ehretia); manifested as pits, or hair tufts. Leaf anatomy. Stomata present; anomocytic. Adaxial hypodermis absent. Lamina dorsiventral, or isobilateral. Cystoliths absent. Minor leaf veins without phloem transfer cells (Ehretia). Stem anatomy. Cork cambium present; initially superficial. Primary vascular tissue in a cylinder, without separate bundles. Secondary thickening developing from a conventional cambial ring. The secondary phloem stratified into hard (fibrous) and soft (parenchymatous) zones. Primary medullary rays narrow. Reproductive type, pollination. Plants hermaphrodite (usually), or andromonoecious (sometimes, in Cordia). Inflorescence, floral, fruit and seed morphology. Flowers solitary (in Cordia, Halgania), or aggregated in ‘inflorescences’; in cymes, in spikes, in heads, in corymbs, and in panicles. The ultimate inflorescence unit cymose. Inflorescences terminal, or axillary, or leaf-opposed; cymose, sometimes spiciform or capitate. Flowers regular; (4–)5(–8) merous; cyclic; tetracyclic. Free hypanthium absent. Hypogynous disk present. Perianth with distinct calyx and corolla; (9–)10(–13); 2 whorled; isomerous, or anisomerous. Calyx (4–)5; 1 whorled; gamosepalous; lobulate, or blunt-lobed, or toothed; campanulate, or tubular; unequal but not bilabiate, or regular; persistent; accrescent (sometimes, inflated and enclosing the fruit), or non-accrescent. Corolla (4–)5(–8) (lobed); 1 whorled; gamopetalous; imbricate (usually), or valvate (sometimes); regular; pink, or purple, or blue. Androecium 5. Androecial members adnate (epipetalous); all equal; free of one another (usually), or coherent (joined by the anthers in Halgania); 1 whorled. Androecium exclusively of fertile stamens. Stamens 5; usually isomerous with the perianth; oppositisepalous; alternating with the corolla members. Anthers separate from one another (usually), or cohering (forming a tube enclosing the style, in Halgania); dehiscing via longitudinal slits; introrse; tetrasporangiate. Endothecium developing fibrous thickenings. Microsporogenesis simultaneous. The initial microspore tetrads tetrahedral, or isobilateral, or decussate. Anther wall initially with one middle layer; of the ‘dicot’ type. Tapetum glandular. Pollen grains aperturate; 3 aperturate; 2-celled. Gynoecium 2 carpelled. Carpels reduced in number relative to the perianth. The pistil 2–4 celled. Gynoecium syncarpous; synovarious to eu-syncarpous; superior. Ovary 2 locular (morphologically, but the locules sometimes with incomplete false septa). Locules secondarily divided by ‘false septa’, or without ‘false septa’. Gynoecium median. Styles 1, or 2, or 4; partially joined; apical. Stigmas 2–4 lobed. Placentation axile to basal. Ovules (1–)2 per locule; ascending (usually), or pendulous (rarely); non-arillate; hemianatropous; unitegmic; tenuinucellate, or crassinucellate. Embryo-sac development Polygonum-type, or Allium-type. Polar nuclei fusing prior to fertilization. Antipodal cells formed; 3; not proliferating; ephemeral. Synergids hooked. Endosperm formation cellular. Endosperm haustoria present; chalazal and micropylar. Embryogeny asterad, or chenopodiad. Fruit fleshy, or non-fleshy; indehiscent (usually), or a schizocarp (Coldenia). Mericarps in Coldenia, 4; comprising nutlets. Fruit a drupe (often enclosed in the persistent calyx); (1–)2–4 seeded. Seeds endospermic, or non-endospermic. Embryo achlorophyllous (1/2). Seedling. Germination phanerocotylar. Physiology, biochemistry. Not cyanogenic. Alkaloids present. Iridoids not detected. Saponins/sapogenins absent. Sugars transported as sucrose (in 9 Cordia and Gerascanthus species, and one Ehretia). C3. C3 physiology recorded directly in Ehretia. Geography, cytology. Sub-tropical to tropical. Pantropical, centring on Central and South America. Taxonomy. Subclass Dicotyledonae; Tenuinucelli. Dahlgren’s Superorder Solaniflorae; Boraginales. Cronquist’s Subclass Asteridae; Lamiales. APG 3 core angiosperms; core eudicot; Superorder Asteranae; lamiid; Order unassigned to Order (as a synonym of Boraginaceae). Species 400. Genera about 13; Bourreria, Coldenia, Cordia (including Gerascanthus), Cortesia, Ehretia, Halgania, Menais(?), Rhabdia. Illustrations. |
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