The families of flowering plants
The families of flowering plants | |
~ 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 pistil 3 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).
This description is offered for casual browsing only. We strongly advise against extracting comparative information from it. This is much more easily achieved using 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).
Cite this publication as: ‘Watson, L., and Dallwitz, M.J. 1992 onwards. The families of flowering plants: descriptions, illustrations, identification, and information retrieval. Version: 19th December 2012. http://delta-intkey.com’.
