Decaschistia Wight & Arn.
Prodr.Fl.Ind.Orient. 52 (1834)

Name Status: Current
Browse to the list of specimens for Decaschistia Wight & Arn.

Scientific Description
S. Hamilton-Brown, Thursday 8 September 2016

Family Malvaceae.

Tribe Decaschiatieae.

Habit and leaf form. Shrubs, or herbs (usually with an indumentum of stellate hairs). Plants unarmed. Annual, or perennial; to 0.2–1 m high. Mesophytic. Heterophyllous. Leaves medium-sized; alternate; spiral; petiolate; non-sheathing; simple. Leaf blades dorsiventral; dissected (3–5-lobed), or entire; ovate, or oblong, or elliptic; palmately lobed; pinnately veined, or palmately veined; cordate, or cuneate at the base, or rounded at the base (or truncate). Mature leaf blades adaxially pubescent; abaxially pubescent. Leaves with stipules (stipules entire or lobed). Stipules caducous. Leaf blade margins entire, or dentate. Leaf anatomy. Hairs present; complex hairs present. Complex hairs stellate. Extra-floral nectaries present (a prominent basal nectary gland on the lower surface of the leaf).

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

Inflorescence and flower features. Flowers solitary, or aggregated in ‘inflorescences’; axillary; in racemes (apparently a leafy raceme). Inflorescences terminal. Flowers pedicellate; medium-sized; regular; 5 merous; tetracyclic. Hypogynous disk absent. Perianth with distinct calyx and corolla; 10; 2 -whorled; isomerous. Calyx present; 5; 1 -whorled; gamosepalous; lobed; lobulate (5-lobed); valvate; exceeded by the corolla; campanulate; regular; persistent. Calyx lobes ovate, or triangular. Epicalyx present (of free persistent bracteoles). Corolla present; 5; 1 -whorled; polypetalous (adnate to the base of the staminal column); plain, or with contrasting markings (darker colour base); white, or red, or purple (i.e. white or mauve or reddish-purple with a red or maroon bases). Petals obovate. Androecium present. Androecial members indefinite in number. Androecium 50–100 (i.e. ‘many’). Androecial members adnate; all equal; coherent (connate; the filaments fused in a column surrounding the style); 1 - adelphous (the tube attached to the petals); 1 -whorled. Androecium exclusively of fertile stamens (or rather, half-stamens, each having only a half anther). Stamens 50–100; remaining included. Anthers dehiscing via longitudinal slits; introrse; unilocular. Gynoecium 8–10 carpelled. The pistil 8–10 celled. Gynoecium syncarpous; synstylovarious to eu-syncarpous; superior. Ovary plurilocular; 8–10 locular. Gynoecium stylate. Styles 1; more than 4-branched (8–10-branched); apical. Stigmas 8–10; capitate. Placentation axile. Ovules 1 per locule.

Fruit and seed features. Fruit 9–13 mm long; non-fleshy; hairy; dehiscent; a capsule (depressed globular). Capsules loculicidal (dehiscing by 8–10 valves). Dispersal unit the seed. Seeds 1 per locule. Seeds not compressed (reniform); conspicuously hairy, or not conspicuously hairy.

Geography, cytology, number of species. World distribution: tropical Asia. Native of Australia. Not endemic to Australia. Australian states and territories: Western Australia, Northern Territory, and Queensland. Northern Botanical Province. A genus of c. 16 species; 2 species in Western Australia; 1 endemic to Western Australia.

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.
  • Craven, L. A.; Fryxell, P. A. (1989). Two new species of Decaschistia (Malvaceae) from Australia.