~ Boraginaceae
Including Cordiaceae R.Br.
Habit and leaf form. Trees, or shrubs, or herbs (rarely). Mesophytic. Leaves alternate (rarely sub-opposite); spiral; non-sheathing; simple. Lamina entire; pinnately veined; cross-venulate. Leaves exstipulate. Lamina margins entire, or serrate. Leaves without a persistent basal meristem. Domatia recorded (Cordia, Ehretia); represented by 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. Hermaphrodite.
Inflorescence, floral, fruit and seed morphology. Flowers aggregated in `inflorescences'; in cymes, in spikes, and in heads. The terminal inflorescence unit cymose. Inflorescences terminal, or axillary, or leaf-opposed; cymose, sometimes spiciform or capitate. Flowers regular; (4-)5(-6) merous; cyclic; tetracyclic. Free hypanthium absent. Hypogynous disk present.
Perianth with distinct calyx and corolla; (9-)10(-11); 2 whorled; isomerous, or anisomerous. Calyx 5; 1 whorled; gamosepalous; lobulate, or lobed, or toothed; campanulate, or tubular; regular; persistent; accrescent (sometimes, inflated and enclosing the fruit), or non-accrescent. Corolla (4-)5(-6) (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; 1 - whorled. Androecium exclusively of fertile stamens. Stamens 5; usually isomerous with the perianth; oppositisepalous. Anthers 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. Carpels reduced in number relative to the perianth. Gynoecium syncarpous; synovarious to synstylovarious; superior. Ovary 2-4 locular (the locules sometimes with incomplete false septa). Gynoecium median. Styles 1, or 2; partially joined; apical. Stigmas 2-4 - lobed. Placentation axile to basal. Ovules 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; a drupe (often enclosed in the persistent calyx); 4 seeded. Seeds endospermic, or non-endospermic. Embryo achlorophyllous (1/2).
Seedling. Germination phanerocotylar.
Physiology, biochemistry. Not cyanogenic. Alkaloids present. Iridoids absent. Saponins/sapogenins absent. C3. C3 recorded 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. Takhtajan's Subclass Asteridae; Lamianae; Polemoniales. Species 400. Genera about 13; Bourreria, Coldenia, Cordia, Cortesia, Ehretia, Halgania, Menais(?), Rhabdia.
Illustrations. ehret463.gif ehret573.gif ehret628.gif ehret570.gif
