The families of flowering plants
Habit and leaf form. Herbs. Perennial; with a basal aggregation of leaves (and acaulescent); rhizomatous, or tuberous (starchy). Mesophytic. Leaves alternate; spiral; petiolate; more or less sheathing. Leaf sheaths not tubular; with free margins. Leaves simple (usually), or compound. Lamina dissected, or entire; when entire lanceolate, or ovate; when dissected (i.e. occasionally) pinnatifid, or palmatifid (or bifid); pinnately veined, or palmately veined; cross-venulate.
General anatomy. Accumulated starch other than exclusively pteridophyte type.
Leaf anatomy. Stomata present; anomocytic, or axillocytic.
Minor leaf veins without phloem transfer cells. Vessels absent.
Stem anatomy. Secondary thickening absent. Xylem without vessels. Sieve-tube plastids P-type; type II.
Root anatomy. Roots with velamen (single layered), or without velamen. Root xylem without vessels (vessel tracheids).
Reproductive type, pollination. Plants hermaphrodite. Pollination entomophilous; via diptera.
Inflorescence, floral, fruit and seed morphology. Flowers aggregated in inflorescences; in umbels. The ultimate inflorescence unit cymose. Inflorescences pedunculate; axillary; cymose umbels; with involucral bracts (these leafy). Flowers individually bracteate (the bracts long, filiform); regular; 3 merous; cyclic; pentacyclic. Perigone tube present (campanulate).
Perianth of tepals; 6; joined; 2 whorled; isomerous; all more or less petaloid; similar in the two whorls; green, or purple, or brown.
Androecium 6. Androecial members adnate (to the perianth tube); free of one another; 2 whorled. Androecium exclusively of fertile stamens. Stamens 6; diplostemonous; petaloid (the filaments adnate to the perianth except for their inflexed margins, but with a petaloid apical extension hooding the anther). Anthers adnate; non-versatile; dehiscing via longitudinal slits; introrse; bilocular; tetrasporangiate. The endothecial thickenings girdling. Anther epidermis persistent. Microsporogenesis simultaneous. The initial microspore tetrads tetrahedral. Anther wall initially with more than one middle layer (2); of the dicot type. Tapetum glandular. Pollen shed as single grains. Pollen grains aperturate; 1 aperturate; sulcate; 2-celled.
Gynoecium 3 carpelled; partly petaloid. Carpels isomerous with the perianth. The pistil 1 celled. Gynoecium syncarpous; eu-syncarpous; inferior. Ovary 1 locular. Epigynous disk present, or absent. Gynoecium stylate. Styles 1; apical. Stigmas 1; 3 lobed (the lobes petaloid); dry type; papillate; Group II type. Placentation parietal. Ovules in the single cavity 15–100 (many); pendulous; non-arillate; anatropous to campylotropous; bitegmic; crassinucellate. Outer integument not contributing to the micropyle. Embryo-sac development Polygonum-type. Polar nuclei fusing prior to fertilization. Antipodal cells formed; 3; not proliferating; ephemeral. Synergids pear-shaped. Endosperm formation nuclear.
Fruit dehiscent, or indehiscent; a capsule, or a berry. Seeds endospermic. Endosperm oily. Seeds without starch. Embryo well differentiated (small). Cotyledons 1 (lateral, the plumule nearly terminal). Testa without phytomelan.
Seedling. Hypocotyl internode present. Seedling collar not conspicuous. Cotyledon hyperphyll non-assimilatory; probably bifacial. Coleoptile absent. Seedling cataphylls absent. First leaf dorsiventral. Primary root ephemeral.
Physiology, biochemistry. Not cyanogenic. Alkaloids present (lactone, 2 species). Proanthocyanidins absent. Flavonols absent. Ellagic acid absent.
Geography, cytology. Holarctic, Paleotropical, Neotropical, and Australian. Sub-tropical to tropical. Pantropical. N = 15.
Taxonomy. Subclass Monocotyledonae. Dahlgren et al. Superorder Liliiflorae; Dioscoreales. APG 3 core angiosperms; Superorder Lilianae; non-commelinid Monocot; Order Dioscoreales.
Species 31. Genera 1; only genus, Tacca (including Schizocapsa).
Illustrations. • Technical details: Tacca, Ataccia (= Tacca). • Tacca: fructiferous branch.
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’.