Habit and leaf form. Shrubs, or lianas; often early deciduous, or evergreen. Plants semi- succulent, or non-succulent. Plants with a basal concentration of leaves, or with neither basal nor terminal concentrations of leaves. Climbing (usually), or self supporting; when climbing, stem twiners. Hydrophytic (M. horrida occurring in seasonal freshwater lakes), or helophytic to xerophytic. Leaves fasciculate, or not fasciculate; alternate, or opposite; spiral; ‘herbaceous’, or fleshy; petiolate, or sessile; sheathing. Leaf sheaths not tubular; with free margins. Leaves gland-dotted, or not gland-dotted; simple; sometimes almost peltate, or not peltate; epulvinate. Leaf blades entire; pinnately veined; cross-venulate; cordate, or hastate, or cuneate at the base. Leaves with stipules. Stipules intrapetiolar; concrescent; ochreate (ochreae soon lacerated and vanishing); scaly. Leaf blade margins entire (or crisped), or serrate; flat, or revolute. Leaves without a persistent basal meristem. Stem anatomy. Nodes penta-lacunar to multilacunar. Secondary thickening absent, or developing from a conventional cambial ring, or anomalous.
Reproductive type, pollination. Fertile flowers functionally male and functionally female, or hermaphrodite, functionally male, and functionally female. Unisexual flowers present. Plants dioecious (usually), or polygamodioecious, or monoecious. Female flowers with staminodes (filaments barren or with minute anthers). Anemophilous, or entomophilous.
Inflorescence and flower features. Flowers aggregated in ‘inflorescences’. Inflorescences terminal, or axillary; mostly branched and paniculate but occasionally appearing as whorl-like bracteate clusters; with involucral bracts, or without involucral bracts. Flowers small; regular; 2 merous, or 3 merous, or 5 merous; cyclic to partially acyclic. When partially acyclic, the perianth acyclic and the androecium acyclic. Free hypanthium present. Hypogynous disk present (or nectaries present between the androecial members); annular. Perianth ambiguously with distinct calyx and corolla, or sepaline, or petaline, or of ‘tepals’ (depending on interpretation); (4–)5; 1 -whorled, or 2 -whorled (or spiralled); joined (at the base); when biseriate, similar in the two whorls, or different in the two whorls; green, or yellow, or white; becoming fleshy (in fruit), or non-fleshy (then membranous); persistent; accrescent. Fertile stamens present, or absent (female flowers). Androecium (6–)8. Androecial members branched, or unbranched; free of the perianth, or adnate (usually more or less perigynous ?); all equal, or markedly unequal; free of one another, or coherent (filaments basally connate ?); when cyclic, 2 -whorled (3+3, or spiralled). Androecium exclusively of fertile stamens. Stamens (6–)8. Anthers dorsifixed, or basifixed; versatile, or non-versatile; dehiscing via longitudinal slits; introrse, or extrorse and introrse, or latrorse; tetrasporangiate. Fertile gynoecium present, or absent (male flowers). Gynoecium (2–)3 carpelled. The pistil 1 celled. Carpels isomerous with the perianth (when P cyclic). Gynoecium syncarpous; synovarious to synstylovarious; superior. Ovary unilocular; 1 locular. Locules secondarily divided by ‘false septa’ (or incompletely trilocular by false septa), or without ‘false septa’. The ‘odd’ carpel posterior. Gynoecium stylate (sometimes only shortly). Styles 3; free to partially joined; more or less fringed; apical. Stigmas 3; dry type; papillate, or non-papillate; Group II type. Placentation basal. Ovules in the single cavity 1; funicled, or sessile; ascending; non-arillate; orthotropous to anatropous.
Fruit and seed features. Fruit non-fleshy; indehiscent; achene-like, or a nut (trigonous); enclosed in the fleshy perianth; 1 seeded. Seeds endospermic. Endosperm ruminate, or not ruminate; oily. Perisperm present to absent (‘more or less absent’ ?). Seeds with starch. Cotyledons 2. Embryo straight to curved. Seedling. Germination phanerocotylar.
Physiology, biochemistry. Aluminium accumulation not found. Plants accumulating free oxalates. Photosynthetic pathway: C3 and C4.
Geography, cytology, number of species. Native of Australia. Not endemic to Australia. Australian states and territories: Western Australia, South Australia, Northern Territory, Queensland, New South Wales, Victoria, Australian Capital Territory, and Tasmania. South-West Botanical Province.