Habit and leaf form. Shrubs, or lianas. Climbing, or self supporting (then straggling). Leaves opposite; leathery; petiolate; simple. Leaf blades entire. Leaves with stipules (stipules small), or without stipules. Stipules interpetiolar, or intrapetiolar. Leaf blade margins entire, or serrate. Leaves without a persistent basal meristem. Leaf anatomy. Hairs absent. Stem anatomy. Nodes unilacunar. Secondary thickening developing from a conventional cambial ring.
Reproductive type, pollination. Fertile flowers hermaphrodite. Unisexual flowers absent. Plants hermaphrodite.
Inflorescence and flower features. Flowers solitary, or aggregated in ‘inflorescences’; axillary; in cymes. The terminal inflorescence unit cymose, or racemose. Inflorescences axillary. Flowers small; regular; 4 merous. Free hypanthium present; adnate to the lower half of the ovary wall, above which the perianth members and stamens separate. Hypogynous disk present, or absent. Perianth with distinct calyx and corolla, or sepaline (the presence of petals can vary among different flowers of the same individual); 4, or 8; 1 -whorled, or 2 -whorled; isomerous. Calyx 4; 1 -whorled; gamosepalous (basally); imbricate; regular; persistent; accrescent. Corolla when present, 4 (then minute, alternating with the calyx); 1 -whorled; regular. Androecium 8. Androecial members free of the perianth, or adnate (each petal segment, when present, basally adnate with the stamen filament in the same radius above the level of separation from the ovary); all equal; free of one another; 2 -whorled. Androecium exclusively of fertile stamens. Stamens 8; diplostemonous. Anthers almost basifixed; non-versatile; dehiscing via longitudinal slits; latrorse to introrse. Pollen shed as single grains. Gynoecium 4 carpelled. The pistil 4 celled. Gynoecium syncarpous; synovarious; partly inferior (one-quarter to half inferior). Ovary plurilocular; 4 locular. Styles 4; partially joined (separating near apex only). Stigmas 4; dry type; papillate; Group II type. Placentation axile. Ovules 1 per locule; pendulous; non-arillate; anatropous.
Fruit and seed features. Fruit non-fleshy; indehiscent; a nut. Seeds endospermic. Endosperm oily. Seeds small. Cotyledons 2. Embryo straight. Micropyle zigzag.
Geography, cytology, number of species. Native of Australia. Endemic to Australia. Australian states and territories: Western Australia, Queensland, and New South Wales. South-West Botanical Province.