Habit and leaf form. Herbs; evergreen; bearing essential oils. Plants unarmed. Annual. Leaves cauline. Plants with neither basal nor terminal concentrations of leaves. Young stems cylindrical. To 0.3–0.7 m high. Leaves small to medium-sized; not fasciculate; opposite; not decurrent on the stems; not imbricate; petiolate; aromatic, or foetid, or without marked odour; simple; epulvinate. Leaf blades entire; flat; ovate, or orbicular; pinnately veined, or palmately veined; cross-venulate; broadly cuneate at the base (to truncate). Mature leaf blades adaxially glabrous; abaxially glabrous. Leaves without stipules. Leaf blade margins crenate (to lobed); flat. Leaves without a persistent basal meristem. Leaf anatomy. Hairs absent; glandular hairs present. Urticating hairs absent. Stem anatomy. Secondary thickening developing from a conventional cambial ring.
Reproductive type, pollination. Fertile flowers hermaphrodite. Unisexual flowers absent. Plants hermaphrodite. Entomophilous, or ornithophilous; usually via hymenoptera, or via lepidoptera, or via diptera.
Inflorescence and flower features. Flowers aggregated in ‘inflorescences’. Inflorescence few-flowered. Flowers in verticils. The terminal inflorescence unit cymose. Inflorescences axillary; axillary in upper leaf axils, usually few-flowered clusters. Flowers small to medium-sized; very irregular; slightly zygomorphic; cyclic; tetracyclic. Floral receptacle developing a gynophore, or with neither androphore nor gynophore. Free hypanthium absent. Perianth with distinct calyx and corolla; 4–10; 2 -whorled; isomerous, or anisomerous. Calyx present; 5; 1 -whorled; gamosepalous; blunt-lobed, or toothed; imbricate, or open in bud; more or less equalling the corolla to exceeding the corolla; broadly funnel-shaped, or campanulate; regular; persistent; with the median member posterior. Corolla present; disguisedly 5; 1 -whorled; gamopetalous; blunt-lobed; imbricate; bilabiate (the lower lip with two narrow lateral lobes and a broad spathulate median, the upper lip oblong, hooded, slightly 2-lobed); with contrasting markings; white to pink (with mauve markings). Corolla lobes oblong (and spathulate). Corolla members entire. Androecium present. Fertile stamens present. Androecial members definite in number. Androecium 4. Androecial members adnate; all equal, or markedly unequal; free of one another; 1 -whorled. Androecium exclusively of fertile stamens. Stamens 4; remaining included; didynamous, or not didynamous, not tetradynamous; reduced in number relative to the adjacent perianth; fertile stamens representing the posterior-lateral pair and the anterior-lateral pair; oppositisepalous; all alternating with the corolla members. Anthers connivent, or separate from one another; dorsifixed; versatile, or non-versatile; dehiscing via longitudinal slits; introrse; unilocular to bilocular; tetrasporangiate; unappendaged. Pollen shed as single grains. Fertile gynoecium present. Gynoecium 2 carpelled (the carpels deeply lobed to mimic G4). The pistil 4 celled. Carpels reduced in number relative to the perianth. Gynoecium syncarpous; synstylovarious to eu-syncarpous; superior. Ovary plurilocular; 2 locular (originally), or 4 locular (by intrusions of the ovary wall constituting ‘ false septa’). Locules secondarily divided by ‘false septa’. Gynoecium median. Styles 1; from a depression at the top of the ovary (the ovary deeply lobed); ‘gynobasic’. Stigmas 2, or 1 (by reduction); 2 - lobed. Placentation basal. Ovules 2 per locule, or 1 per locule (two per original loculus, but one per locellus); ascending; apotropous; non-arillate; anatropous, or hemianatropous.
Fruit and seed features. Fruit non-fleshy, or fleshy; a schizocarp. Mericarps (2–)4; comprising nutlets. Seeds endospermic to non-endospermic. Embryo well differentiated. Cotyledons 2. Embryo straight.
Special features. The flowering nodes separated by extended internodes. 3–5 flowers subtended by each floral leaf. Calyx limb 5 lobed. Corolla tube not exceeding the calyx. The upper lip of the corolla incorporating 2 members, the lower 3; (posterior, adaxial) lip of the corolla entire to bilobed; upper (adaxial) lip of the corolla markedly concave. Lower (abaxial) lip of the corolla 3 lobed. Stamens ascending.
Geography, cytology, number of species. Adventive. Not endemic to Australia. Australian states and territories: Western Australia, South Australia, New South Wales, and Victoria. A genus of 4 species; 1 species in Western Australia; 0 endemic to Western Australia.
Etymology. After the Molucca Islands, where the plant was thought to have originated.