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Villarsia Vent.
Choix.Pl.Buitenzorg Tab.9 (1803)

Name Status: Not Current

Scientific Description
H.R. Coleman, Thursday 8 September 2016

Family Menyanthaceae.

Habit and leaf form. Tufted herbs. Annual, or perennial. Leaves basal (only), or basal and cauline (the cauline leaves sometimes reduced to bracts, usually becoming progressively less leaf-like from the base of the plant upward). Plants with a basal concentration of leaves; sometimes with stolons, the perennial species having a thickened rootstock. Hydrophytic, or helophytic; when hydrophytic, rooted. Leaves submerged, or emergent, or floating; alternate; spiral; petiolate (petiole winged and semi-sheathing toward the base); sheathing; simple. Leaf blades entire; pinnately veined, or palmately veined; cross-venulate; cordate, or rounded at the base. Leaves without stipules. Leaf blade margins entire, or crenate, or dentate. Leaves without a persistent basal meristem. Leaf anatomy. Hydathodes present. Stem anatomy. Nodes tri-lacunar, or penta-lacunar. Secondary thickening absent, or developing from a conventional cambial ring.

Reproductive type, pollination. Fertile flowers hermaphrodite. Unisexual flowers absent. Plants hermaphrodite. Plants heterostylous, or homostylous. Floral nectaries present (glands 5, often orange, small). Entomophilous.

Inflorescence and flower features. Flowers aggregated in ‘inflorescences’; in heads, or in fascicles, or in panicles. The terminal inflorescence unit cymose, or racemose. Inflorescences scapiflorous, or not scapiflorous. Flowers pedicellate to sessile; small to medium-sized; regular; (4–)5(–6) merous; cyclic; tetracyclic. Free hypanthium absent. Hypogynous disk present; intrastaminal. Perianth with distinct calyx and corolla; (9–)10(–11); 2 -whorled; isomerous, or anisomerous (rarely). Calyx 5; 1 -whorled; polysepalous, or gamosepalous (sometimes connate); hairy, or glabrous; regular; persistent. Corolla (4–)5(–6); 1 -whorled; appendiculate, or not appendiculate; gamopetalous (with a tube); valvate (or induplicate-valvate); regular; yellow, or white. Corolla members conspicuously fringed (at the throat). Androecium 5. Androecial members adnate (to the tube); free of one another. Stamens 5; isomerous with the perianth; oppositisepalous; filantherous, or with sessile anthers (almost sessile). Anthers narrowly ovate to linear in outline; versatile; dehiscing via longitudinal slits; introrse; tetrasporangiate. Gynoecium 2 carpelled. The pistil 1 celled. Carpels reduced in number relative to the perianth. Gynoecium syncarpous; synstylovarious; superior, or partly inferior. Ovary unilocular; 1 locular. Gynoecium median; stylate. Styles 1; apical; becoming exserted. Stigmas 2(–3); wet type; papillate; Group III type. Placentation parietal (2(-3) placentas). Ovules in the single cavity 10–100 (‘many’); horizontal; anatropous.

Fruit and seed features. Fruit fleshy, or non-fleshy; dehiscent; a capsule. Capsules usually dehiscent at the summit by 4 valves, sometimes breaking irregularly. Fruit 4–100 seeded (‘few to many’). Seeds endospermic. Endosperm oily. Cotyledons 2. Embryo straight. Testa smooth, or with tubercles.

Geography, cytology, number of species. Native of Australia. Not endemic to Australia. Australian states and territories: Western Australia, South Australia, New South Wales, Victoria, Australian Capital Territory, and Tasmania. South-West Botanical Province.