Taccaceae Dumort.

Scientific Description

Common name. Tacca Family.

Habit and leaf form. Herbs. Perennial; plants with a basal concentration 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. Leaf blades dissected, or entire; when entire lanceolate, or ovate; when dissected (i.e. occasionally) pinnatifid, or palmately lobed (or bifid); pinnately veined, or palmately veined; cross-venulate. Stem anatomy. Secondary thickening absent. Roots. Roots with velamen (single layered), or without velamen.

Reproductive type, pollination. Fertile flowers hermaphrodite. Unisexual flowers absent. Plants hermaphrodite. Entomophilous; via diptera.

Inflorescence and flower features. Flowers aggregated in ‘inflorescences’; in umbels. The terminal 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; 2 -whorled; isomerous; 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. Pollen shed as single grains. Gynoecium 3 carpelled. The pistil 1 celled. Gynoecium partly petaloid. Carpels isomerous with the perianth. Gynoecium syncarpous; eu-syncarpous; inferior. Ovary unilocular; 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.

Fruit and seed features. Fruit dehiscent, or indehiscent; a capsule, or a berry. Seeds endospermic. Endosperm oily. Seeds without starch. Embryo well differentiated (small). Cotyledons 1. Seedling. Hypocotyl internode present. Mesocotyl absent. Seedling collar not conspicuous. Cotyledon hyperphyll non-assimilatory. Coleoptile absent. Seedling cataphylls absent. First leaf dorsiventral. Primary root ephemeral.

Geography, cytology, number of species. Holarctic, Paleotropical, Neotropical, and Australian. World distribution: pantropical. N = 15. 31 species.