Habit and leaf form. Herbaceous climbers; evergreen. Perennial. Leaves cauline. Plants with neither basal nor terminal concentrations of leaves. Young stems branching, leafy, prickly or smooth. Rhizomatous (starch rich). Climbing; petiole twiners (twisted), or tendril climbers (a pair of tendrils at the junction of the petiole and the sheath, or these may be reduced to short points). Mesophytic, or xerophytic. Leaves alternate; leathery; petiolate (more or less winged below the tendrils, twisted); sheathing (rarely), or non-sheathing. Leaf sheaths if present, with free margins. Leaves foetid, or without marked odour; simple. Leaf blades entire; lanceolate, or ovate; broadly elliptic to ovate, or orbicular; one-veined, or palmately veined (3–7 (in W.A. 5) prominent converging veins, the outer pair often indistinct, primary veins converging, secondary veins usually reticulate); cross-venulate; cordate, or hastate, or attenuate at the base. Leaves with stipules (more or less well developed, adnate, ending in tendrils, narrow or broad, sometimes inflated), or without stipules. Leaf blade margins entire. Leaf anatomy. Hairs absent. Extra-floral nectaries absent. Stem anatomy. Secondary thickening absent.
Reproductive type, pollination. Fertile flowers functionally male, or functionally female. Unisexual flowers present. Plants dioecious. Female flowers with staminodes (small). Male flowers with pistillodes, or without pistillodes. Entomophilous.
Inflorescence and flower features. Flowers aggregated in ‘inflorescences’; in umbels (cymose), or in panicles (umbellate). Inflorescences not scapiflorous; terminal, or axillary; inflorescence pedunculate, simple or branched, umbels many-flowered. Flowers pedicellate (15–25 mm long); bracteate (very small, subtend each pedicel, imbricate); ebracteolate; regular; 3 merous; cyclic. Perigone tube present, or absent. Perianth of ‘tepals’; 6; 2 -whorled; isomerous; free, or joined; petaloid; similar in the two whorls to different in the two whorls; (inner segments) green, or white, or cream, or pink, or purple; deciduous. Fertile stamens present, or absent (female flowers). Androecial members definite in number. Androecium 6. Androecial members adnate; all equal; free of one another; 2 -whorled. Androecium exclusively of fertile stamens. Stamens 6 (usually in 2 whorls); all more or less similar in shape; diplostemonous; at the base of the perianth segments. Anthers basifixed; dehiscing via pores, or dehiscing via longitudinal slits; introrse, or latrorse; unilocular, or bilocular (becoming 1); tetrasporangiate. Pollen shed as single grains. Fertile gynoecium present, or absent (male flowers). Gynoecium 3 carpelled. The pistil 3 celled. Carpels isomerous with the perianth. Gynoecium syncarpous; synovarious to synstylovarious; superior. Ovary plurilocular; 3 locular; sessile. Gynoecium non-stylate, or stylate (very short). Styles 3; free, or partially joined; apical. Stigmas 1. Placentation axile. Ovules 1(–2) per locule; pendulous; non-arillate; orthotropous, or hemianatropous, or campylotropous.
Fruit and seed features. Fruit fleshy; indehiscent; a berry; 1-few. Seeds endospermic. Endosperm oily. Embryo well differentiated; straight. Testa without phytomelan.
Etymology. The name of an ancient Greek plant possibly belonging to this genus.