Habit and leaf form. Small, woody shrubs (subshrubs, with cystoliths). Young stems 4–6-angled. Hydrophytic, or helophytic, or mesophytic, or xerophytic. Leaves opposite (the pairs connected by transverse ridge); petiolate to subsessile; gland-dotted, or not gland-dotted; simple. Leaf blades entire; flat; pinnately veined, or palmately veined; cross-venulate. Leaves without stipules. Leaf blade margins entire, or crenate, or dentate (or irregular); flat, or revolute, or involute. Stem anatomy. Nodes unilacunar. Secondary thickening developing from a conventional cambial ring. Roots. Aerial roots present, or absent.
Reproductive type, pollination. Fertile flowers hermaphrodite. Unisexual flowers absent. Plants hermaphrodite. Entomophilous. Pollination mechanism conspicuously specialized, or unspecialized.
Inflorescence and flower features. Flowers solitary, or aggregated in ‘inflorescences’; when solitary, axillary; in spikes. The terminal inflorescence unit cymose, or racemose. Inflorescences terminal, or axillary; loose; pseudanthial, or not pseudanthial. Flowers bracteate; bi- bracteolate, or ebracteolate (? obscure); very irregular; zygomorphic. The floral asymmetry involving the perianth. Flowers 5 merous; tetracyclic. Free hypanthium absent. Hypogynous disk present; annular (or urceolate, 2 small rectangular appendages on rim). Perianth with distinct calyx and corolla; 10; 2 -whorled; isomerous. Calyx 5; 1 -whorled; gamosepalous (free almost to base); lobed; regular (more or less equal); hyaline along margin; with the median member posterior. Corolla 5; 1 -whorled; gamopetalous; imbricate, or contorted, or with open aestivation; bilabiate. Androecium 2. Androecial members adnate; all equal; free of one another; 1 -whorled. Stamens 2. Staminal insertion in tube with dense V-shaped ciliate region at point of insertion. Stamens becoming exserted; reduced in number relative to the adjacent perianth; oppositisepalous; all alternating with the corolla members. Anthers dehiscing via longitudinal slits; bilocular (cells inserted at unequal levels on an oblique connective); tetrasporangiate; appendaged. The anther appendages basal. Pollen shed as single grains. Gynoecium 2 carpelled. The pistil 2 celled. Gynoecium syncarpous; synstylovarious to eu-syncarpous; superior. Ovary plurilocular; 2 locular. Gynoecium median. Ovary sessile. Styles 1; attenuate from the ovary; apical; much longer than the ovary at anthesis. Stigmas 1; 1 - lobed; sometimes distinctly capitate; dry type; non-papillate; Group II type. Placentation axile. Ovules 2 per locule; superposed; non-arillate, or arillate; hemianatropous, or anatropous, or campylotropous.
Fruit and seed features. Fruit non-fleshy; dehiscent; a capsule (club-shaped, apex acute, base solid). Capsules loculicidal. Fruit elastically dehiscent. Dispersal unit the seed. Seeds more or less ovate; non-endospermic; conspicuously hairy, or not conspicuously hairy. Embryo well differentiated. Cotyledons 2. Embryo achlorophyllous; curved. Testa verrucose. Seedling. Germination phanerocotylar.
Physiology, biochemistry. Aluminium accumulation not found.
Special features. The seeds on elongated, indurated, hook-shaped funicles (‘retinacula’). The upper (posterior, adaxial) lip of the corolla bilobed (notched); upper (adaxial) lip of the corolla shorter than lower lip, convex, with glabrous style channel. Lower (abaxial) lip of the corolla deeply 3 lobed; middle lobe with glabrous palate of 2 longitudinal upraised folds, lateral lobes spreading almost at right angles to middle lobe.
Geography, cytology, number of species. Native of Australia. Endemic to Australia. Australian states and territories: Western Australia, Northern Territory, Queensland, and New South Wales. Eremaean Botanical Province.