Habit and leaf form. Herbs; evergreen; bearing essential oils. Plants unarmed. Annual, or perennial. Leaves cauline. Plants with neither basal nor terminal concentrations of leaves. Young stems tetragonal. Stem internodes solid, or hollow. To 0.3–1.2 m high. Self supporting, or climbing. Leaves small to medium-sized; opposite; not decurrent on the stems; not imbricate; petiolate; aromatic; simple; epulvinate. Leaf blades entire; flat; ovate to oblong (-ovate); pinnately veined; cross-venulate; cuneate at the base (to obtuse), or attenuate at the base. Mature leaf blades adaxially glabrous; abaxially glabrous, or pilose (at least on veins). Leaves without stipules. Leaf blade margins crenate to dentate, or serrate; flat. Leaves without a persistent basal meristem. Leaf anatomy. 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; 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 terminal and axillary; verticillasters 6-flowered, secund, in axillary and terminal raceme-like inflorescences. Flowers pedicellate; bracteate; ebracteolate; very small; very irregular; zygomorphic. The floral asymmetry involving the perianth and involving the androecium. Flowers cyclic; tetracyclic. Floral receptacle developing a gynophore, or with neither androphore nor gynophore. Free hypanthium absent. Hypogynous disk present, or absent. Perianth with distinct calyx and corolla; 4–10; 2 -whorled; isomerous, or anisomerous (or only dubiously interpretable). Calyx present; 5; 1 -whorled; gamosepalous; unequally blunt-lobed and toothed (the 2 abaxial and 2 lateral lobes subequal, much narrower than the single adaxial lobe); imbricate, or open in bud; exceeded by the corolla; campanulate, or tubular; more or less bilabiate; non-fleshy; persistent; with the median member posterior. Calyx lobes ovate. Corolla present; disguisedly 5; 1 -whorled; gamopetalous; imbricate; tubular to campanulate; bilabiate (abaxial lobe entire, adaxial and lateral lobes short and broad); plain; white, or purple, or pink (flesh coloured). Corolla lobes oblong. Corolla members entire. Androecium present. Fertile stamens present. Androecial members definite in number. Androecium 4. Androecial members adnate; markedly unequal; free of one another; 1 -whorled. Androecium exclusively of fertile stamens. Stamens 4; becoming exserted; didynamous; all more or less similar in shape; 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. Filaments glabrous; filiform. 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 pistil 4 celled. Carpels reduced in number relative to the perianth. Gynoecium syncarpous; synstylovarious to eu-syncarpous; superior. Ovary plurilocular; 2 locular, or 4 locular. Locules secondarily divided by ‘false septa’. Gynoecium median; stylate. Styles 1; simple; from a depression at the top of the ovary; ‘gynobasic’; becoming exserted. Stigmas 2, or 1; 2 - lobed. Placentation basal. Ovules 2 per locule, or 1 per locule; ascending; apotropous; non-arillate; anatropous, or orthotropous.
Fruit and seed features. Fruit non-fleshy; a schizocarp. Mericarps 4; comprising nutlets. Seeds endospermic to non-endospermic; minute. Embryo well differentiated. Cotyledons 2. Embryo straight.
Special features. The flowering nodes aggregated in dense spicate inflorescences. 1–2 flowers subtended by each floral leaf. Calyx limb 5 lobed. Upper lip of calyx entire. Lower lip of calyx lobed. Corolla tube not exceeding the calyx. The upper (posterior, adaxial) lip of the corolla entire. Lower (abaxial) lip of the corolla 3 lobed.
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. A genus of 2 species, or 3 species; 1 species in Western Australia; 0 endemic to Western Australia.
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Western Australian Herbarium (1998–). FloraBase—the Western Australian Flora. Department of Biodiversity, Conservation and Attractions. https://florabase.dpaw.wa.gov.au/