Tacca J.R.Forst. & G.Forst.
Char.Gen.Pl. p35 (1775)

Name Status: Current
Browse to the list of specimens for Tacca J.R.Forst. & G.Forst.

Scientific Description
J. Gathe and Leslie Watson, Thursday 8 September 2016

Family Taccaceae.

Habit and leaf form. Herbs. Perennial. Leaves basal. Plants with a basal concentration of leaves (and acaulescent); rhizomatous, or tuberous (starchy). Mesophytic. Leaves alternate; spiral; petiolate (petiole long, erect, ribbed, usually solid); 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; broadly elliptic, or ovate; when dissected (i.e. occasionally) pinnatifid, or palmately lobed (or bifid); pinnately veined, or palmately veined; cross-venulate; more or less widened. Leaf anatomy. Hairs absent. Extra-floral nectaries absent. 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, the scape radical, unbranched, leafless, ribbed, usually solid, the herbaceous peduncle usually directly from the perennating organ; with involucral bracts (these 4–12 or rarely 2 in 2 whorls, surrounding the inflorescence, usually erect, large, thin, herbaceous, deciduous). Flowers pedicellate; individually bracteate (the bracts long, filiform); ebracteolate; regular; 3 merous; cyclic; pentacyclic. Perigone tube present (campanulate). Perianth of ‘tepals’; 6; 2 -whorled; isomerous; all more or less petaloid; similar in the two whorls; green (greenish), or purple, or purple and brown (dark brown-purple). Androecial members definite in number. Androecium 6. Androecial members adnate (filaments apart from the inflexed margins fused to the perianth); all equal; free of one another; 2 -whorled. Androecium exclusively of fertile stamens. Stamens 6; all more or less similar in shape; diplostemonous; on the perianth segments; petaloid (the filaments adnate to the perianth except for their inflexed margins, but with a petaloid apical extension hooding the anther). Filaments appendiculate. 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 3; 3 - lobed (the lobes petaloid, bifid). 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; 10–100 seeded (10 to many). Seeds endospermic. Endosperm oily. Embryo well differentiated (small). Cotyledons 1.

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

Etymology. Probably a Malayan name.

Taxonomic Literature

  • Wheeler, J. R.; Rye, B. L.; Koch, B. L.; Wilson, A. J. G.; Western Australian Herbarium (1992). Flora of the Kimberley region. Western Australian Herbarium. Como, W.A.
  • Australia. Bureau of Flora and Fauna (1986). Flora of Australia. Volume 46, Iridaceae to Dioscoreaceae. Australian Govt. Pub. Service. Canberra.