Sphenotoma (R.Br.) Sweet
Fl.Australas. 44 (1827)

Name Status: Current
Browse to the list of specimens for Sphenotoma (R.Br.) Sweet

Scientific Description
H.R. Coleman, Friday 3 October 2008

Family Epacridaceae.

Habit and leaf form. Shrubs; evergreen; leptocaul, or pachycaul. Helophytic to xerophytic. Leaves small to medium-sized; alternate; spiral, or four-ranked; ‘herbaceous’, or leathery; imbricate; petiolate to sessile; sheathing. Leaf sheaths with free margins. Leaves simple. Leaf blades entire; flat; parallel-veined; cross-venulate, or without cross-venules. Leaves without stipules. Leaf blade margins flat. Stem anatomy. Nodes tri-lacunar to multilacunar (? Richeoideae having 3 or more vascular traces to each leaf). Secondary thickening developing from a conventional cambial ring.

Reproductive type, pollination. Fertile flowers hermaphrodite. Unisexual flowers absent. Plants hermaphrodite. Entomophilous, or ornithophilous. Pollination mechanism unspecialized.

Inflorescence and flower features. Flowers aggregated in ‘inflorescences’; in spikes, or in heads. Inflorescences simple; axillary. Flowers bracteate. Bracts persistent. Flowers bracteolate; small; fragrant, or odourless; regular; 5 merous; cyclic; tetracyclic. Free hypanthium absent. Hypogynous disk present, or absent; intrastaminal; of separate members, or annular. Perianth with distinct calyx and corolla; 10; 2 -whorled; isomerous. Calyx 5; 1 -whorled; polysepalous; imbricate; exceeded by the corolla; regular; persistent. Corolla 5; 1 -whorled; gamopetalous; lobed (lobes horizontally spreading). Corolla lobes markedly shorter than the tube, or about the same length as the tube. Corolla imbricate; tube narrow, the throat almost closed by longitudinal folds at the base of the lobes; regular; white; persistent, or deciduous. Androecium 5. Androecial members adnate (to the corolla); all equal; free of one another; 1 -whorled. Androecium exclusively of fertile stamens. Stamens 5; isomerous with the perianth; oppositisepalous; all alternating with the corolla members. Anthers basifixed, or adnate; becoming inverted during development, their morphological bases ostensibly apical in the mature stamens; non-versatile; dehiscing via longitudinal slits (by a single median slit); finally introrse (inverting during development); unilocular, or bilocular; bisporangiate; unappendaged. Pollen shed in aggregates, or shed as single grains; without viscin strands; in diads, or in triplets, or in tetrads. Gynoecium 5 carpelled. The pistil 5 celled. Gynoecium syncarpous; eu-syncarpous; superior. Ovary plurilocular; 5 locular. Gynoecium stylate. Styles 1; from a depression at the top of the ovary; apical. Stigmas 1; truncate, or clavate, or capitate. Placentation axile. Ovules 3–20 per locule (i.e. ‘several’); pendulous; non-arillate; anatropous.

Fruit and seed features. Fruit non-fleshy; dehiscent; a capsule. Capsules loculicidal. Seeds endospermic. Endosperm oily. Seeds wingless. Embryo well differentiated. Cotyledons 2. Embryo straight. Seedling. Germination phanerocotylar.

Physiology, biochemistry. Aluminium accumulation not found. Photosynthetic pathway: C3.

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

Additional characters Prophylls few.

Taxonomic Literature

Wheeler, Judy; Marchant, Neville; Lewington, Margaret; Graham, Lorraine (2002). Flora of the south west, Bunbury, Augusta, Denmark. Volume 2, dicotyledons. Australian Biological Resources Study. Canberra.

Blackall, William E.; Grieve, Brian J. (1981). How to know Western Australian wildflowers : a key to the flora of the extratropical regions of Western Australia. Part IIIB, (Epacridaceae-Lamiaceae). University of W.A. Press. Perth.