Habit and leaf form. Herbs. Plants with roots; unarmed; autotrophic. Annual. Leaves basal, or cauline. Plants with a basal concentration of leaves, or with neither basal nor terminal concentrations of leaves, or with terminal rosettes of leaves. Young stems slender, tetragonal. To 0.1–0.6 m high. Mesophytic. Heterophyllous. Leaves small, or medium-sized; not fasciculate; opposite; decussate; not decurrent on the stems; ‘herbaceous’; not imbricate; usually petiolate (but becoming sessile up the stem). Petioles wingless. Leaves without marked odour; with ‘normal’ orientation; simple; not peltate; epulvinate. Leaf blades dorsiventral; entire; flat; ovate (to broadly so); prominently 3 -nerved (but rarely 5-nerved); parallel-veined; without cross-venules; when petiolate, rounded at the base. Mature leaf blades adaxially glabrous; abaxially glabrous. Leaves without stipules. Leaf blade margins entire; flat. Leaf anatomy. Hairs absent. Stem anatomy. Secondary thickening absent. Roots. Aerial roots absent.
Reproductive type, pollination. Fertile flowers hermaphrodite. Unisexual flowers absent. Plants hermaphrodite. Plants not viviparous; homostylous. Floral nectaries absent. Entomophilous.
Inflorescence and flower features. Flowers aggregated in ‘inflorescences’; not crowded at the stem bases. Inflorescence many-flowered. Flowers in cymes. Inflorescences compound. The terminal inflorescence unit cymose. Inflorescences terminal (or terminating axillary branchlets); ascending; usually an open diffuse compound dichasium. Flowers pedicellate; minutely bracteolate; small; odourless; regular, or somewhat irregular (rarely). The floral asymmetry (when manifest) involving the perianth (corolla and androecium only). Flowers 4 merous; cyclic; tetracyclic. Free hypanthium absent. Hypogynous disk present. Perianth with distinct calyx and corolla; 8; 2 -whorled; isomerous. Calyx present; 4; 1 -whorled; gamosepalous; lobed; lobulate. Calyx lobes markedly shorter than the tube. Calyx prominently 8 veined; erect; glabrous; exceeded by the corolla; tubular; regular; persistent. Calyx lobes narrowly ovate. Corolla present; 4; 1 -whorled; gamopetalous; lobed; lobulate. Corolla lobes markedly shorter than the tube. Corolla imbricate; tubular (salverform); regular; glabrous abaxially; glabrous adaxially; pink, or orange, or purple; persistent. Corolla lobes oblong to obovate. Androecium present. Androecial members definite in number. Androecium 4. Androecial members adnate (to corolla tube); markedly unequal (1 longer than the other 3); free of one another; 1 -whorled. Stamens 4; isomerous with the perianth; all alternating with the corolla members. Filaments glabrous; filiform. Anthers all alike; basifixed; non-versatile; dehiscing via longitudinal slits. Gynoecium 2 carpelled. The pistil 1 celled. Carpels reduced in number relative to the perianth. Gynoecium syncarpous; synstylovarious; superior. Ovary unilocular; 1 locular; sessile. Ovary summit glabrous. Gynoecium stylate. Styles 1; apical; deciduous; hairless. Stigmas 2. Placentation parietal.
Fruit and seed features. Fruit 3–4.5 mm long; shortly stipitate; non-fleshy; not hairy; dehiscent; a capsule. Capsules dehiscing longitudinally to base. Dispersal unit the seed. Fruit 30–50 seeded (‘many’). Cotyledons 2.
Geography, cytology, number of species. Paleotropical. World distribution: cosmopolitan. Native of Australia. Not endemic to Australia. Australian states and territories: Western Australia, Northern Territory, and Queensland. Northern Botanical Province. 2n = 36. A genus of 30 species; 1 species in Western Australia; C. diffusa.
Etymology. From Kansjan -cora, name of C. perfoliata in Malabar.