Badly in need of revision (Kessler 1993:122).
Habit and leaf form. Trees (in Australia). ‘Normal’ plants. Leaves well developed. Plants with roots; unarmed; autotrophic. To 20 m high (in Australia). Self supporting. Mesophytic. Not heterophyllous. Leaves medium-sized; alternate; distichous (in Australia); with blades; leathery (‘subcoriaceous’); petiolate; simple; not peltate; epulvinate. Leaf blades neither inverted nor twisted through 90 degrees; entire; flat; elliptic (in Australia). Mature leaf blades adaxially sparsely pubescent, or glabrous; abaxially sparsely pubescent, or glabrous. Leaves without stipules. Leaf blade margins entire; flat. Leaf anatomy. Hairs absent, or present.
Reproductive type, pollination. Fertile flowers hermaphrodite (in Australia). Unisexual flowers absent (in Australia). Plants hermaphrodite (in Australia). Plants homostylous.
Inflorescence and flower features. Flowers solitary; axillary (rarely 2 together); pedicellate; small; regular; not resupinate; 3 merous; cyclic; pentacyclic. Perianth with distinct calyx and corolla; 9; 3 -whorled; isomerous. Calyx present; 3; 1 -whorled; polysepalous; sparsely appressed hairy; valvate; regular. Sepals ovate. Corolla present; 6; 2 -whorled (outer whorl similar in shape and size to sepals); polypetalous; valvate; sparsely appressed hairy abaxially; sparsely appressed hairy adaxially; fleshy (inner whorl), or not fleshy. Petals elliptic (outer whorl), or ovate (inner whorl). Androecium present. Fertile stamens present. Androecial members definite in number, or indefinite in number. Androecium 3–100 (‘few to numerous’). Androecial members free of one another. Stamens 100 (‘numerous’); isomerous with the perianth to polystemonous. Anthers separate from one another; dehiscing via longitudinal slits; tetrasporangiate. Fertile gynoecium present. Gynoecium 100 carpelled (‘numerous’). Carpels isomerous with the perianth, or increased in number relative to the perianth. Gynoecium apocarpous; eu-apocarpous; partly inferior. Carpel stylate; apically stigmatic; 1–10 ovuled.
Fruit and seed features. Fruit 9–12 mm long (in Australia). The fruiting carpel indehiscent. Dispersal unit the seed.
Geography, cytology, number of species. Native of Australia. Endemic to Australia. Australian states and territories: Western Australia, Northern Territory, and Queensland. Northern Botanical Province. A genus of ca 40–50 species; 1 species in Western Australia; M. brahei (F.Muell.) Jessup; 0 endemic to Western Australia.