Habit and leaf form. Shrubs; laticiferous, or non-laticiferous and without coloured juice, or with coloured juice. Plants succulent, or non-succulent. Mesophytic, or xerophytic. Leaves small to medium-sized; alternate; spiral, or distichous; ‘herbaceous’, or leathery, or fleshy; petiolate to sessile; non-sheathing; gland-dotted, or not gland-dotted; simple. Leaf blades entire; rolled; pinnately veined. Leaves without stipules. Leaf blade margins entire; revolute (or recurved). Leaves without a persistent basal meristem. Leaf anatomy. Urticating hairs present, or absent. Stem anatomy. Nodes tri-lacunar, or unilacunar. Secondary thickening developing from a conventional cambial ring, or anomalous; from a single cambial ring.
Reproductive type, pollination. Fertile flowers functionally male, or functionally female. Unisexual flowers present. Plants monoecious. Female flowers solitary (and adjacent to a male flower or surrounded by several male flowers). Male flowers solitary, or aggregated in ‘inflorescences’; without pistillodes. Entomophilous.
Inflorescence and flower features. Flowers solitary, or aggregated in ‘inflorescences’; terminal, or axillary (apparently, when terminating short flowering branches); in racemes, or in fascicles. Inflorescences terminal. Flowers pedicellate; bracteate. Bracts scale-like. Flowers bi- bracteolate; minute to medium-sized; regular; 4–6 merous. Floral receptacle developing an androphore, or with neither androphore nor gynophore (? depending on interpretation). Free hypanthium absent. Hypogynous disk present, or absent. Perianth with distinct calyx and corolla; 8–12; 2 -whorled; isomerous. Calyx 4–6; gamosepalous (basally connate); regular; often not persistent, or persistent. Corolla 4–6 (alternating with glands); polypetalous; regular; often deciduous, or persistent. Fertile stamens present, or absent (female flowers). Androecium 20–1000 (i.e. ‘numerous’). Androecial members branched, or unbranched; free of the perianth; free of one another (if filaments interpreted as arising from an androphore), or coherent (connate into a central column, the filaments shortly free below the anthers). Androecium exclusively of fertile stamens. Stamens 20–1000; polystemonous; erect in bud, or inflexed in bud. Anthers dehiscing via longitudinal slits; extrorse, or introrse; bisporangiate, or tetrasporangiate. Fertile gynoecium present, or absent (male flowers). Gynoecium 3 carpelled. The pistil 3 celled. Gynoecium syncarpous; synovarious, or synstylovarious (? depending on interpretation of partially connate styles); superior. Ovary plurilocular; 3 locular. Styles 3; partially joined (connate at the base); forked; apical. Stigmas 6; dry type; papillate, or non-papillate; Group II type. Placentation axile, or apical. Ovules 1 per locule; pendulous; epitropous; with ventral raphe, or with dorsal raphe; arillate; orthotropous, or anatropous, or hemianatropous.
Fruit and seed features. Fruit non-fleshy; a schizocarp (capsular). Mericarps 3; 2-valved. Fruit elastically dehiscent (schizocarpic capsules often splitting elastically), or passively dehiscent. Seeds cylindric; endospermic. Endosperm oily. Seeds arillate. Cotyledons 2 (usually wider than the radicle). Embryo straight, or curved. Testa smooth. Seedling. Germination phanerocotylar, or cryptocotylar.
Physiology, biochemistry. Mustard-oils present, or absent.
Geography, cytology, number of species. Native of Australia. Endemic to Australia. Australian states and territories: Western Australia. Northern Botanical Province and South-West Botanical Province.