Macarthuria Endl.

Scientific Description

Family Molluginaceae.

Habit and leaf form. Herbs, or shrubs; non-laticiferous and without coloured juice. ‘Normal’ plants. Leaves well developed. Plants with roots; non-succulent; unarmed; autotrophic. Perennial. Leaves cauline, or cauline and basal (rarely). To 1.5(–2) m high. Self supporting. Mesophytic. Not heterophyllous. Leaves minute, or small, or medium-sized; alternate; with blades and bladeless (progressively reduced up the stem), or bladeless (rarely); ‘herbaceous’ and membranous, or membranous (scales); petiolate, or subsessile; simple; not peltate; epulvinate. Leaf blades neither inverted nor twisted through 90 degrees; dorsiventral (in Australia); entire; flat; various. Mature leaf blades adaxially glabrous, or pubescent (rarely); abaxially glabrous, or pubescent (rarely). Leaves eligulate; without stipules. Leaf blade margins entire; flat. Leaf anatomy. Hairs absent, or present (rarely).

Reproductive type, pollination. Fertile flowers hermaphrodite. Unisexual flowers absent. Plants hermaphrodite. Plants homostylous.

Inflorescence and flower features. Flowers aggregated in ‘inflorescences’, or solitary (rarely). Inflorescence many-flowered, or few-flowered. Flowers in cymes. Inflorescences compound. The terminal inflorescence unit cymose. Inflorescences axillary, or terminal. Flowers pedicellate; ebracteolate; small; regular; not resupinate; 5 merous; cyclic; tetracyclic, or tricyclic (rarely). Free hypanthium absent, or present (rarely). Hypogynous disk present, or absent (rarely). Perianth with distinct calyx and corolla, or sepaline; 5 (rarely), or 10; 3 -whorled, or 2 -whorled (rarely); isomerous, or anisomerous (rarely). Calyx present; 5; 2 -whorled; polysepalous (in Australia); imbricate; non-fleshy. Sepals elliptic to ovate. Corolla present, or absent; 0, or 5; 1 -whorled; polypetalous; glabrous abaxially; glabrous adaxially; white to cream. Androecium present. Fertile stamens present. Androecial members definite in number (in Australia). Androecium 8. Androecial members coherent (connate at the base); 1 - adelphous; 2 -whorled. Stamens 8; alternisepalous. Anthers separate from one another; dehiscing via longitudinal slits; tetrasporangiate. Fertile gynoecium present. Gynoecium 3 carpelled. The pistil 3 celled. Carpels reduced in number relative to the perianth. Gynoecium syncarpous; synovarious to synstylovarious; superior. Ovary plurilocular, or unilocular (rarely); 3 locular. Gynoecium stylate. Styles 3; partially joined (at the base). Stigmas 3; 1 - lobed. Placentation basal; axile. Ovules in the single cavity 1; 1–3 per locule; anatropous to campylotropous.

Fruit and seed features. Fruit 1.5–4 mm long; dehiscent; a capsule. Capsules loculicidal. Dispersal unit the seed. Fruit 1–10 seeded (‘few’). Seeds non-endospermic. Perisperm present. Seeds small; arillate.

Geography, cytology, number of species. Native of Australia. Endemic to Australia. Australian states and territories: Western Australia, Northern Territory, Queensland, and New South Wales. Northern Botanical Province and South-West Botanical Province. A genus of ca 10 species; 6 species in Western Australia; 5 endemic to Western Australia.