Stemonaceae Caruel

Scientific Description

Common name. Stemona Family.

Habit and leaf form. Herbs, or herbaceous climbers, or lianas, or shrubs (shrublets). Perennial; plants with neither basal nor terminal concentrations of leaves; rhizomatous, or tuberous. Self supporting, or climbing; sometimes stem twiners. Stemona twining anticlockwise. Mesophytic. Leaves alternate, or opposite, or whorled; when alternate, distichous; ‘herbaceous’, or leathery; petiolate; non-sheathing; simple. Leaf blades entire; convergent palmately veined; cross-venulate; cordate (often), or attenuate at the base, or rounded at the base. Leaf blade margins entire. Stem anatomy. Secondary thickening absent.

Reproductive type, pollination. Fertile flowers hermaphrodite (usually), or functionally male and functionally female. Unisexual flowers present, or absent (usually). Plants hermaphrodite (usually), or monoecious.

Inflorescence and flower features. Flowers solitary, or aggregated in ‘inflorescences’; in cymes, or in racemes. The terminal inflorescence unit cymose, or racemose. Inflorescences axillary; few flowered cymes or racemes, the pedicels articulated. Flowers bracteate (and axillary), or ebracteate; small, or medium-sized; sometimes malodorous; regular; 2 merous; cyclic; pentacyclic, or tricyclic. Perigone tube present, or absent. Perianth of ‘tepals’; 4; 2 -whorled; isomerous (2+2); sepaloid, or petaloid; similar in the two whorls. Fertile stamens present, or absent (female flowers). Androecium 4. Androecial members adnate; free of one another, or coherent (Stemona, where the broad stamens are basally connate, and have an internal extension that contacts the stigma); often 1 - adelphous (the filaments connate); 1 -whorled, or 2 -whorled. Androecium exclusively of fertile stamens. Stamens 4; diplostemonous. Anthers basifixed; dehiscing via longitudinal slits; introrse; tetrasporangiate; appendaged (apically), or unappendaged. Pollen shed as single grains. Fertile gynoecium present, or absent (male flowers). Gynoecium 2 carpelled. The pistil 1 celled. Carpels reduced in number relative to the perianth. Gynoecium syncarpous; synstylovarious; superior, or partly inferior (Stichoneuron). Ovary unilocular; 1 locular. Gynoecium non-stylate, or stylate. Styles apical. Placentation basal (Stemona), or apical (Stichoneuron). Ovules in the single cavity 3–50 (‘few to several’, or ‘many’); horizontal, or ascending; arillate; orthotropous, or anatropous.

Fruit and seed features. Fruit non-fleshy; dehiscent, or indehiscent; a capsule, or capsular-indehiscent. Capsules sometimes two valvular. Seeds 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. Holarctic, Paleotropical, and Australian. World distribution: Southeast Asia, Malaysia, Northern Australia. X = 7. 23 species.