Stemona Lour.

Scientific Description

Family Stemonaceae.

Habit and leaf form. Herbs, or shrubs. Leaves well developed (may be absent at flowering). Herbs perennial; plants with neither basal nor terminal concentrations of leaves; rhizomatous, or tuberous. Self supporting, or climbing; sometimes stem twiners. Twining anticlockwise. Mesophytic. Leaves alternate; spiral; ‘herbaceous’, or leathery; petiolate; non-sheathing; simple. Leaf blades entire; ovate to triangular, or linear; convergent palmately veined; cross-venulate. Leaf blade margins entire. Stem anatomy. Secondary thickening absent.

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

Inflorescence and flower features. Flowers solitary, or aggregated in ‘inflorescences’; when solitary axillary. Inflorescence few-flowered. Flowers in cymes, or in racemes. The terminal inflorescence unit cymose, or racemose. Inflorescences axillary (in axils of leaves or scale leaves on apparently leafless stems). Flowers pedicellate. Pedicels articulated, the ‘pedicel’ above the articulation representing the slender, elongate base of the flower receptacle. Flowers bracteate; small, or medium-sized; regular; 2 merous; cyclic; pentacyclic. Perigone tube present, or absent. Perianth of ‘tepals’; 4; 2 -whorled; isomerous (2+2); petaloid; similar in the two whorls; purple, or red to black. Androecium 4. Androecial members adnate (to the perianth); coherent (the broad stamens basally connate, with an internal extension that contacts the stigma); 1 - adelphous; 2 -whorled. Androecium exclusively of fertile stamens. Stamens 4; diplostemonous; more or less petaloid (due to the enlarged connectives). Filaments appendiculate (connectives much elongated above the anther cells, broad, somewhat petal-like). Anthers basifixed; dehiscing via longitudinal slits; introrse; tetrasporangiate; appendaged. The anther appendages apical (filiform, horn-like). Pollen shed as single grains. Gynoecium 2 carpelled. The pistil 1 celled. Carpels reduced in number relative to the perianth. Gynoecium syncarpous; synstylovarious; superior. Ovary unilocular; 1 locular. Gynoecium non-stylate, or stylate (sessile to subsessile). Styles apical. Placentation basal. Ovules in the single cavity 3–5 (i.e. ‘few’); ascending; arillate; orthotropous.

Fruit and seed features. Fruit non-fleshy; dehiscent; a capsule (ovoid, somewhat compressed). Capsules two valvular. Seeds ovoid, with appendages to the long funicle; endospermic. Endosperm not ruminate; oily. Seedling. Hypocotyl internode absent. Mesocotyl absent. Seedling collar not conspicuous. Cotyledon hyperphyll compact; non-assimilatory. Coleoptile absent. Seedling cataphylls present. First leaf dorsiventral. Primary root persistent.

Geography, cytology, number of species. Native of Australia. Not endemic to Australia. Australian states and territories: Western Australia, Northern Territory, and Queensland. Northern Botanical Province. X = 7.

Additional characters Pollen grains sulcate.