Poranthera Rudge

Scientific Description

Family Euphorbiaceae.

Habit and leaf form. Shrubs, or herbs; non-laticiferous and without coloured juice. Plants succulent, or non-succulent. Mesophytic, or xerophytic. Leaves minute to medium-sized; alternate (or subopposite); spiral, or distichous; ‘herbaceous’, or leathery, or fleshy; petiolate to sessile; non-sheathing; gland-dotted, or not gland-dotted; simple. Leaf blades entire; flat, or rolled; pinnately veined, or palmately veined. Leaves with stipules. Stipules pale, membranous, entire or toothed; caducous, or persistent. Leaf blade margins flat, or revolute. Leaves without a persistent basal meristem. Leaf anatomy. Hairs absent. Urticating hairs present, or absent. Stem anatomy. Nodes tri-lacunar, or unilacunar. Secondary thickening developing from a conventional cambial ring, or anomalous; from a single cambial ring.

Reproductive type, pollination. Fertile flowers functionally male, or functionally female. Unisexual flowers present. Plants monoecious. Male flowers with pistillodes (rudimentary ovary small, tripartite), or without pistillodes. Entomophilous.

Inflorescence and flower features. Flowers aggregated in ‘inflorescences’; in cymes, or in racemes (each flower head usually with several small male and female flowers). Inflorescences simple, or compound (usually forming terminal leafy corymbs or panicles); terminal, or axillary; pedunculate, head-like; without involucral bracts, or with involucral bracts (? subtended by leaf-like bracts). Flowers pedicellate; bracteate, or ebracteate; minute to small; regular; 5 merous. Free hypanthium absent. Hypogynous disk present; annular. Perianth with distinct calyx and corolla; 10; 2 -whorled; isomerous. Calyx petal-like, 5, or 3 (rarely); gamosepalous (shortly connate at the base); imbricate; regular. Corolla much smaller than the sepals, each with a small gland at the base 5, or 3 (rarely); gamopetalous (shortly connate at the base); regular. Fertile stamens present, or absent (female flowers). Androecium 5, or 3 (rarely). Androecial members free of the perianth; free of one another. Androecium exclusively of fertile stamens. Stamens 5, or 3 (rarely); isomerous with the perianth; oppositisepalous; erect in bud, or inflexed in bud. Anthers dehiscing via pores (with apical pores); extrorse, or introrse; four locular (the cells globular, distinct); bisporangiate, or tetrasporangiate. Fertile gynoecium present, or absent (male flowers). Gynoecium 3 carpelled. The pistil 3 celled. Gynoecium syncarpous; synovarious, or synstylovarious; superior. Ovary plurilocular; 3 locular; glabrous, 6-ribbed. Styles 3; free, or partially joined; forked (divided almost to the base or merely notched); apical. Stigmas 6; dry type; papillate, or non-papillate; Group II type. Placentation axile, or apical. Ovules 2 per locule; pendulous; epitropous; with ventral raphe, or with dorsal raphe; collateral; non-arillate; anatropous.

Fruit and seed features. Fruit non-fleshy; a schizocarp (a depressed globular capsule, opening in 3 or 6 valves, the valves usually separating more readily than the cocci). Mericarps 3. Fruit elastically dehiscent (schizocarpic capsules often splitting elastically), or passively dehiscent. Seeds trigonous; endospermic. Endosperm oily. Seeds non-arillate. Cotyledons 2 (about as wide as the radicle). Embryo curved. Seedling. Germination phanerocotylar, or cryptocotylar.

Physiology, biochemistry. Mustard-oils present, or absent.

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. Northern Botanical Province, Eremaean Botanical Province, and South-West Botanical Province.