(Subfamily Byttnerioideae), Tribe Dombeyeae.
Habit and leaf form. Shrubs, or herbs; non-laticiferous and without coloured juice. ‘Normal’ plants. Leaves well developed. Plants with roots; non-succulent. Leaves cauline. To 0.5–1 m high. Self supporting. Mesophytic. Not heterophyllous. Leaves medium-sized, or large; alternate; with blades; petiolate (to 15mm). Petioles wingless. Leaves with ‘normal’ orientation; simple; not peltate. Leaf blades neither inverted nor twisted through 90 degrees; dorsiventral (dark green above, paler green below); entire; flat; ovate (or cordate); pinnately veined; cross-venulate; rounded at the base, or cordate, or oblique at the base (rarely). Mature leaf blades adaxially glabrous, or pubescent (sparsely); abaxially pubescent (very densely stellate hairy). Leaves with stipules. Stipules intrapetiolar; free of the petiole; free of one another; spiny. Leaf blade margins entire, or crenate, or serrate. Leaf anatomy. Hairs present; complex hairs present. Complex hairs stellate.
Reproductive type, pollination. Fertile flowers hermaphrodite. Unisexual flowers absent. Plants hermaphrodite. Plants homostylous.
Inflorescence and flower features. Flowers solitary, or aggregated in ‘inflorescences’; not crowded at the stem bases; terminal, or axillary; in cymes. Inflorescences simple; axillary. Flowers shortly pedicellate; ebracteate; ebracteolate; small; regular; not resupinate; neither papilionaceous or pseudo-papilionaceous; 5 merous; cyclic; tetracyclic. Floral receptacle with neither androphore nor gynophore. Perianth with distinct calyx and corolla; 10; 2 -whorled; isomerous. Calyx present; 5; 1 -whorled; gamosepalous; lobed. Calyx lobes markedly longer than the tube. Calyx hairy (less hairy inside); valvate; slightly exceeding the corolla; regular; neither appendaged nor spurred. Epicalyx present (consisting of 3 bracts often longer than the sepals). Corolla present; 5; 1 -whorled; not appendiculate; polypetalous; contorted; yellow. Androecium present. Fertile stamens present. Androecial members definite in number. Androecium 10. Androecial members free of the perianth; free of the gynoecium; markedly unequal; coherent (connate at the base into a short staminal tube, stamens alternating with 5 ligulate larger staminodes); 1 - adelphous; 1 -whorled. Androecium including staminodes. Staminodes 5; non-petaloid. Stamens 5; all more or less similar in shape; isomerous with the perianth; filantherous. Anthers separate from one another; all alike; dehiscing via longitudinal slits; bilocular (sagittate). Fertile gynoecium present. Gynoecium 5 carpelled. The pistil 5 celled. Carpels isomerous with the perianth. Gynoecium syncarpous; synovarious, or synstylovarious, or eu-syncarpous; superior. Ovary plurilocular; 5 locular; sessile. Gynoecium stylate. Styles 5; partially joined; with 5 subulate branches, stigmatic on the inner surface; apical. Stigmas 25; 1 - lobed; subulate. Placentation axile. Ovules 1–50 per locule (‘one to many’).
Fruit and seed features. Fruit 5–6 mm long; densely hairy; dehiscent; a capsule. Capsules loculicidal (in 5 valves). Dispersal unit the seed. Fruit 1–50 seeded (‘one to many’ per valve). Seeds 1–50 per locule (‘one to many’). Seeds small.
Geography, cytology, number of species. Native of Australia, or adventive. Endemic to Australia, or not endemic to Australia. Australian states and territories: Western Australia, South Australia, Northern Territory, Queensland, and New South Wales. Northern Botanical Province and Eremaean Botanical Province. There is some doubt as to whether M. oblongifolia F.Muell., the only WA taxon in the genus, is an endemic Australian species or whether it is conspecific with M. incana Heynes, a widespread Asian species (Wilson 1992). A genus of ca 60 species; 1 species in Western Australia; 1 endemic to Western Australia.
Additional comments. Named after Mt Melhan in Yemen, from where the type species was described.