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The families of flowering plants.                                                                                                                                                                

Potaliaceae Mart.

                        

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~Gentianaceae, Loganiaceae

Habit and leaf form. Glabrous, unarmed, spiny or prickly trees (to 30 m in Anthocleista and Fagraea), or shrubs, or lianas (in Anthocleista and Fagraea). Self supporting, or epiphytic, or climbing. Leaves opposite; leathery, or leathery to fleshy; petiolate to sessile; connate (the bases ‘usually confluent’); simple. Lamina entire; pinnately veined; cross-venulate. Leaves stipulate, or exstipulate (then the stipules represented by a mere line along the more or less joined leaf bases). Stipules interpetiolar (sometimes represented by a stipular sheath, entire or split into two scales on each side), or intrapetiolar; ochreate, or not ochreate; with colleters; sometimes leafy and ‘secondary’. Lamina margins entire, or crenate.

Leaf anatomy. Mucilaginous epidermis present, or absent. Stomata mostly mainly confined to one surface; anisocytic (commonly), or anomocytic (?). Hairs present, or absent; eglandular, or glandular; unicellular, or multicellular. Unicellular hairs unbranched. Multicellular hairs uniseriate, or multiseriate (e.g., stalked glands in Fagraea); when multicellular, unbranched. Complex hairs present, or absent; (glandular) clavate, or capitate.

Adaxial hypodermis present, or absent. Lamina dorsiventral. The mesophyll with sclerencymatous idioblasts. Minor leaf veins without phloem transfer cells (Fagraea).

Stem anatomy. Secretory cavities absent. Cork cambium present; initially superficial. Cortical bundles present (in Fagraea), or absent (?). Medullary bundles present (in Fagraea), or absent (?). Internal phloem present (‘always’). Secondary thickening anomalous; from a single cambial ring. ‘Included’ phloem present. Xylem without tracheids; without fibre tracheids; with libriform fibres (a few septate fibres recorded only in Fagraea). Vessel end-walls oblique; simple. Vessels with vestured pits. Primary medullary rays narrow (and almost exclusively uniseriate, occasionally partly biseriate). Wood semi-ring porous, or diffuse porous; not storied; parenchyma apotracheal (Potalia), or apotracheal and paratracheal (Anthocleista).

Reproductive type, pollination. Plants hermaphrodite.

Inflorescence, floral, fruit and seed morphology. Flowers solitary, or aggregated in ‘inflorescences’; in cymes, or in racemes, or in fascicles, or in panicles. The ultimate inflorescence unit cymose (mostly), or racemose (by reduction). Inflorescences terminal (usually), or axillary; mostly few to many-flowered cymes, variously shaped. Flowers bracteate (the lower bracts sometimes leafy, otherwise bracts small and scale-like); bracteolate, or ebracteolate; medium-sized, or large (sometimes showy); regular; cyclic; tetracyclic. Free hypanthium absent. Hypogynous disk present (Potalia and Anthocleista spp.), or absent; when present, intrastaminal; annular.

Perianthwith distinct calyx and corolla; 9–21; 2 whorled, or 3 whorled; isomerous, or anisomerous. Calyx 4, or 5; 1 whorled, or 2 whorled (often decussate, e.g. Potalia); gamosepalous (connate below), or gamosepalous; regular; fleshy, or non-fleshy (then leathery); persistent (mostly), or not persistent; non-accrescent; imbricate. Corolla 5–16; 1 whorled; gamopetalous (tubular, with short to long tube). Corolla lobes markedly shorter than the tube to about the same length as the tube. Corolla contorted; campanulate, or funnel-shaped, or hypocrateriform; regular; white (or cream), or yellow, or purple, or blue (or violet), or green (sometimes, at least the tube); fleshy.

Androecium 5–16 (as many as the corolla lobes). Androecial members adnate (to the corolla tube); free of one another, or coherent; when joined, 1 adelphous (the filaments sometimes connected by a ring); 1 whorled. Androecium exclusively of fertile stamens. Stamens 5–16; inserted midway down the corolla tube, or in the throat of the corolla tube; isomerous with the perianth; oppositisepalous; alternating with the corolla members; filantherous, or with sessile anthers. Anthers dorsifixed, or basifixed (Fagraea); dehiscing via longitudinal slits; introrse. Tapetum glandular (at least in Fagraea). Pollen grains aperturate; 3 aperturate; porate (e.g. in Anthocleista vogelii), or colporate (variable in Fagraea, where the furrow varies from long to absent); 2-celled (in Fagraea).

Gynoecium 2 carpelled (unless the 4–celled conditions in Potalia and Anthocleista represent 4 genuine carpels!). Carpels reduced in number relative to the perianth. The pistil 1 celled, or 1–2 celled, or 4 celled (or then diminishing to 2 above). Gynoecium syncarpous; eu-syncarpous; superior. Ovary 1 locular, or 2 locular, or 1–2 locular (Fagraea), or 4 locular (ostensibly, in Anthocleista and also in some Potalia species). Locules secondarily divided by ‘false septa’ (i.e., accounting for the 4–celled gynoecia), or without ‘false septa’. Gynoecium median; stylate. Styles 1 (persistent); apical. Stigmas 1–2; 1–2 lobed; when entire, capitate, or subpeltate. Placentation when unilocular, parietal; when bilocular or four celled, basal to axile. Ovules in the single cavity when unilocular, 6–100 (‘several or many’); 6–50 per locule (‘several or many’); anatropous; unitegmic; tenuinucellate. Endothelium not differentiated. Embryo-sac development Polygonum-type. Polar nuclei fusing only after one has been fertilized, or fusing simultaneously with the male gamete (?). Antipodal cells formed; 3; not proliferating; ephemeral. Synergids pear-shaped. Endosperm formation nuclear.

Fruit fleshy; indehiscent (usually), or dehiscent (occasionally, in Fagraea); a berry (but occasionally 4 valved in large-fruited Fagraea species). Seeds endospermic (endosperm fleshy); wingless. Embryo straight.

Physiology, biochemistry. Not cyanogenic. Alkaloids present (in all the genera). Iridoids detected (Fagraea); ‘Route I’ type. Verbascosides not detected. Cornoside not detected. Proanthocyanidins absent. Aluminium accumulation not found.

Geography, cytology. Tropical. Pantropical. 2n = 60, 66. Supposed basic chromosome number of family: 10 and 11. Ploidy levels recorded: 6.

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 Gentianaceae).

Species 70. Genera 3; Fagraea, Anthocleista, Potalia.

General remarks. These closely related genera (cf. Bentham and Hooker, 1876) have been sunk in Gentianaceae by Struwe et al. (1994). On the basis of the more detailed descriptions attempted here, Gentianaceae are indeed their nearest neighbours (five differences). See comments under Loganicaceae.

 Illustrations:

  • Technical details: Fagraea, Desfontainia.
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