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The families of flowering plants.                                                                                                                                                                

Cobaeaceae D. Don

                       

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~Polemoniaceae

Habit and leaf form. Lianas. Climbing; tendril climbers (the tendrils much branched, with terminal hooks, representing modified terminal leaflets). Leaves alternate; petiolate; compound; pinnate. Lamina pinnately veined; cross-venulate. Leaves stipulate. Stipules intrapetiolar; free of one another; large, leafy.

Leaf anatomy. Minor leaf veins without phloem transfer cells.

Stem anatomy. Secretory cavities present (in the phloem, with yellow secretion). Secondary thickening developing from a conventional cambial ring.

Reproductive type, pollination. Plants hermaphrodite. Pollination entomophilous; via diptera (at first), or via hymenoptera (bees, later); mechanism conspicuously specialized (flowers very protandrous, with movement of the stamens and styles: at first functionally male, then greenish and malodorous, subsequently female, then purple and honey-scented).

Inflorescence, floral, fruit and seed morphology. Flowers solitary to aggregated in ‘inflorescences’. Inflorescences axillary; 1–3 flowered on long, common pedumcles. Flowers large; malodorous (at first), or fragrant (later); regular; 5 merous; cyclic; tetracyclic. Free hypanthium absent. Hypogynous disk present; large, fleshy, lobed.

Perianth with distinct calyx and corolla; 10; 2 whorled; isomerous. Calyx 5; 1 whorled; slightly gamosepalous (at the base), or polysepalous. Calyx lobes when gamosepalous, markedly longer than the tube. Corolla 5; 1 whorled; gamopetalous. Corolla lobes markedly shorter than the tube, or about the same length as the tube. Corolla contorted; campanulate (the lobes linear to rounded).

Androecium 5. Androecial members adnate (to the base of the corolla); all equal; free of one another; 1 whorled. Androecium exclusively of fertile stamens. Stamens 5; inserted near the base of the corolla tube; isomerous with the perianth; filantherous (the filaments bearded below). Anthers dorsifixed; versatile. Endothecium developing fibrous thickenings. Microsporogenesis simultaneous. The initial microspore tetrads tetrahedral. Anther wall initially with one middle layer. Tapetum amoeboid. Pollen grains aperturate; 13–40 aperturate (?); (poly-) foraminate; 2-celled.

Gynoecium 3 carpelled. Carpels reduced in number relative to the perianth. The pistil3 celled. Gynoecium syncarpous; synovarious to synstylovarious (the style shortly trifid); superior. Ovary 3 locular. Gynoecium stylate. Styles 1; partially joined; apical. Stigmas 3; dry type; papillate; Group II type. Placentation axile. Ovules 2–50 per locule (to ‘many’); biseriate, medifixed; anatropous; unitegmic; pseudocrassinucellate. Embryo-sac development Polygonum-type. Endosperm formation nuclear.

Fruit non-fleshy; dehiscent; a capsule. Capsules septicidal. Seeds non-endospermic;winged (and compressed). Embryo well differentiated (large). Cotyledons 2 (large, cordate). Embryo achlorophyllous (2/2).

Seedling.Germination cryptocotylar.

Physiology, biochemistry. Not cyanogenic. Iridoids not detected. Proanthocyanidins present, or absent; cyanidin. Flavonols present; kaempferol and quercetin. Ellagic acid absent. Saponins/sapogenins present.

Geography, cytology. Neotropical. Sub-tropical to tropical. Tropical America.

Taxonomy.Subclass Dicotyledonae; Tenuinucelli. Dahlgren’s Superorder Solaniflorae; Solanales. Cronquist’s Subclass Asteridae; Solanales. APG 3 core angiosperms; core eudicot; Superorder Asteranae; Order Ericales (as a synonym of Polemoniaceae).

Species 18. Genera 1; only genus, Cobaea.

 Illustrations:

  • Cobaea stipularis: Bot. Reg. 25, 1841.
  • Cobaea (Chittenden).
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