Stylobasium Desf.

Scientific Description

Family Surianaceae.

Habit and leaf form. Shrubs; leptocaul. Xerophytic. Leaves small to medium-sized; alternate; leathery; petiolate; non-sheathing; simple. Leaf blades entire; pinnately veined; cross-venulate. Leaves with stipules (then the stipules minute), or without stipules. Leaf blade margins entire. Leaves without a persistent basal meristem. Stem anatomy. Secondary thickening developing from a conventional cambial ring.

Reproductive type, pollination. Fertile flowers hermaphrodite (flowers markedly protandrous, the anthers dehiscing, then falling, before the stigma matures. The various stages of the flowering sequence have caused some confusion about the sexuality of the flowers, being previously described as polygamous or monoecious). Unisexual flowers absent. Plants hermaphrodite. Anemophilous.

Inflorescence and flower features. Flowers solitary, or aggregated in ‘inflorescences’; when solitary, axillary. Inflorescence few-flowered. Flowers in racemes (pseudo-racemes). The terminal inflorescence unit racemose. Inflorescences terminal; short. Flowers bracteolate (minute); small; regular; tetracyclic. Floral receptacle not markedly hollowed. Free hypanthium absent. Hypogynous disk absent. Perianth sepaline (the corolla absent); 5; 1 -whorled. Calyx 5; 1 -whorled; gamosepalous; lobed; imbricate; campanulate (tube obconic); regular; persistent; with the median member posterior. Calyx lobes obtuse. Androecium 10. Androecial members free of the perianth; all equal; free of one another; 2 -whorled. Androecium exclusively of fertile stamens. Stamens 10; becoming exserted; diplostemonous; filantherous. Filaments filiform (persistent). Anthers linear, large; basifixed; straight; dehiscing via longitudinal slits; extrorse. Gynoecium 1 carpelled. The pistil 1 celled. Carpels reduced in number relative to the perianth. Gynoecium monomerous; of one carpel; superior. Carpel stylate; with a gynobasic style (and large, peltate stigma); 2 ovuled. Placentation basal. Ovary glabrous. Styles becoming exserted. Ovules ascending; non-arillate; anatropous.

Fruit and seed features. Fruit fleshy. The fruiting carpel indehiscent; drupaceous (drupe small, obovoid or globular, surrounded by the enlarged calyx). Fruit 1 seeded. Seeds very sparsely endospermic. Seedling. Germination phanerocotylar.

Geography, cytology, number of species. Native of Australia. Endemic to Australia. Australian states and territories: Western Australia, Northern Territory, and Queensland. Northern Botanical Province, Eremaean Botanical Province, and South-West Botanical Province.