Habit and leaf form. Small trees, or shrubs; viscid, laticiferous, or non-laticiferous and without coloured juice, or with coloured juice. Plants succulent, or non-succulent. Mesophytic, or xerophytic. Leaves minute 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; pinnately veined, or palmately veined. Leaves without stipules; without a persistent basal meristem. Leaf anatomy. Hairs present, or absent; complex hairs present. Complex hairs stellate. 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 mostly dioecious, or monoecious. Female flowers solitary. Male flowers aggregated in ‘inflorescences’ (often clustered on recurved peduncles), or solitary (rarely). Entomophilous.
Inflorescence and flower features. Flowers solitary, or aggregated in ‘inflorescences’. Inflorescences axillary. Flowers pedicellate; bracteate, or ebracteate; small; regular; (4–)5 merous. Floral receptacle developing an androphore (filaments crowded on a hemispherical receptacle). Free hypanthium absent. Hypogynous disk present, or absent. Perianth with distinct calyx and corolla, or sepaline; (4–)5, or (9–)10 (when both whorls present); 1 -whorled, or 2 -whorled; when two-whorled, isomerous. Calyx present; (4–)5; gamosepalous (shortly connate at the base); imbricate; regular. Corolla present, or absent; when present, 5 (small); polypetalous; regular. Fertile stamens present, or absent (female flowers). Androecium 20–200 (i.e. ‘numerous’). Androecial members free of the perianth; free of one another. Androecium exclusively of fertile stamens. Stamens 20–200; polystemonous; erect in bud, or inflexed in bud. Filaments short. Anthers linear to oblong in outline; dehiscing via longitudinal slits, or dehiscing via pores (with apical pores); extrorse, or introrse; bilocular to four locular; bisporangiate, or tetrasporangiate. Fertile gynoecium present, or absent (male flowers). Gynoecium 3 carpelled. The pistil 3 celled. Gynoecium syncarpous; synovarious, or synstylovarious; superior. Ovary plurilocular; 3 locular. Gynoecium stylate, or non-stylate (if stigmatic area interpreted as a sessile stigma). Styles if present, 1; simple, or forked (2-lobed); apical. Stigmas 1, or 2; caplike, conical, peltate or lobed; 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; anatropous.
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 1 per mericarp. Seeds endospermic. Endosperm oily. Seeds arillate. Cotyledons 2 (usually wider than the radicle). Embryo straight, or curved. 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, Queensland, New South Wales, Victoria, and Tasmania. Eremaean Botanical Province and South-West Botanical Province.