Habit and leaf form. Shrubs; evergreen; bearing essential oils. Plants unarmed. Leaves cauline. Plants with neither basal nor terminal concentrations of leaves. Young stems usually tetragonal. To 0.2–2 m high. Leaves small to medium-sized; not fasciculate; opposite, or whorled; sessile, or petiolate (shortly); aromatic, or foetid, or without marked odour; simple; epulvinate. Leaf blades entire; flat, or rolled; linear; one-veined, or pinnately veined; cross-venulate; cordate to cuneate at the base, or rounded at the base. Mature leaf blades adaxially scabrous to glabrous; abaxially villous (velutinous). Leaves without stipules. Leaf blade margins entire; revolute. Leaves without a persistent basal meristem. Leaf anatomy. Hairs present; 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 solitary (in the axils), or aggregated in ‘inflorescences’; pedicellate; bracteolate. Bracteoles not adnate to the receptacle. Flowers small to medium-sized; very irregular; 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; prominently 10–15 veined; imbricate, or open in bud; exceeded by the corolla; campanulate; regular; non-fleshy; persistent; with the median member posterior. Calyx lobes narrowly triangular. Corolla present; disguisedly 5; 1 -whorled; gamopetalous; blunt-lobed; imbricate; bilabiate (upper lip concave and slightly emarginate, the lower slightly shorter, with 3 obtuse lobes); hairy abaxially (puberulous with simple and glandular hairs); plain; red. 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 including staminodes (anthers reduced to small connective, with two linear or narrowly clavate lobes). Staminodes 2; representing the anterior-lateral pair. Stamens 2. Staminal insertion midway down the corolla tube, or in the throat of the corolla tube. Stamens remaining included; all more or less similar in shape; reduced in number relative to the adjacent perianth; fertile stamens representing the posterior-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; tetrasporangiate; appendaged. The anther appendages basal. 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; stylate. Styles 1; simple; from a depression at the top of the ovary; apical; much longer than the ovary at anthesis; not becoming exserted; hairless. Stigmas 1; shortly 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; small. Embryo well differentiated. Cotyledons 2. Embryo straight.
Special features. The flowering nodes separated by extended internodes. 1 flowers subtended by each floral leaf. Calyx limb 5 lobed. Corolla tube exceeding the calyx, or not exceeding the calyx; straight, or curved. The upper lip of the corolla incorporating 2 members, the lower 3; (posterior, adaxial) lip of the corolla entire to bilobed (only slightly emarginate); upper (adaxial) lip of the corolla markedly concave. Lower (abaxial) lip of the corolla 3 lobed (spreading); not concave. The appendages of the fertile anthers linear (glabrous or bearded). The appendages of the staminode anthers linear, or clavate (narrowly).
Geography, cytology, number of species. Native of Australia. Endemic to Australia. Australian states and territories: Western Australia. Northern Botanical Province. A genus of 17 species; 19 species in Western Australia; 17 endemic to Western Australia.
Etymology. From the Greek for "small" and "helmet"; refers to the small hooded upper corolla-lobe.
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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/