Hemichroa R.Br.
Prodr.Fl.Nov.Holland. 409 (1810)

Name Status: Current
Browse to the list of specimens for Hemichroa R.Br.

Scientific Description
Leslie Watson, Thursday 8 September 2016

Family Amaranthaceae.

Habit and leaf form. Shrubs, or herbs. Plants succulent. Herbs perennial. Leaves cauline. Plants with neither basal nor terminal concentrations of leaves. Halophytic, in coastal salt-marshes and around inland salt lakes. Leaves alternate to opposite (at least the lowermost usually alternate); not decurrent on the stems; fleshy; sessile; non-sheathing; simple. Leaf blades entire; solid; linear to ovate (mucronate); one-veined. Leaves without stipules. Stem anatomy. Nodes unilacunar. Secondary thickening developing from a conventional cambial ring, or anomalous.

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

Inflorescence and flower features. Flowers solitary; axillary; 1 per axil; sessile; ebracteate (i.e. subtended by leaves); bi- bracteolate. Bracteoles persistent (scarious, rigid). Flowers minute to small; regular; cyclic; tricyclic. Free hypanthium absent. Hypogynous disk absent. Perianth sepaline (dry and membranous); 5; 1 -whorled; free; petaloid; white; non-fleshy; persistent; non-accrescent. Calyx present (the perianth being thus interpreted); 5; 1 -whorled; polysepalous; erect; imbricate; regular; white; non-fleshy; persistent; non-accrescent; with the median member posterior. Sepals narrowly oblong. Corolla absent. Androecial members definite in number. Androecium 2, or 5. Androecial sequence not determinable. Androecial members free of the perianth; all equal, or markedly unequal; coherent; 1 - adelphous (the filaments basally connate into a short cup); 1 -whorled. Androecium exclusively of fertile stamens. Stamens 2 (the adaxial members), or 5; reduced in number relative to the adjacent perianth (H. diandra), or isomerous with the perianth; oppositisepalous. Anthers dorsifixed; dehiscing via longitudinal slits; introrse; bisporangiate, or tetrasporangiate. Pollen shed as single grains. Gynoecium 2–3 carpelled. The pistil 1 celled. Carpels reduced in number relative to the perianth. Gynoecium syncarpous; synstylovarious; superior. Ovary unilocular; 1 locular. Ovary summit glabrous. Gynoecium stylate. Styles 1; forked; attenuate from the ovary; apical. Stigmas 2; dry type; papillate; Group II type. Placentation basal. Ovules in the single cavity 1; non-arillate; campylotropous.

Fruit and seed features. Fruit fleshy, or non-fleshy; indehiscent; capsular-indehiscent (a utricle); 1 celled; 1 locular; 1 seeded. Seeds non-endospermic. Perisperm present (abundant, mealy). Seeds with starch. Embryo well differentiated. Cotyledons 2. Embryo curved. Testa smooth.

Geography, cytology, number of species. Native of Australia. Endemic to Australia. A genus of 3 species; 2 species in Western Australia.

Additional comments. This succulent genus is usually referred to Chenopodiaceae.

Taxonomic Literature

  • Grieve, B. J.; Blackall, W. E. (1998). How to know Western Australian wildflowers : a key to the flora of the extratropical regions of Western Australia. Part II, Dicotyledons (Amaranthaceae to Lythraceae). University of W.A. Press. Nedlands, W.A.
  • Wheeler, J. R.; Rye, B. L.; Koch, B. L.; Wilson, A. J. G.; Western Australian Herbarium (1992). Flora of the Kimberley region. Western Australian Herbarium. Como, W.A.
  • Marchant, N. G.; Wheeler, J. R.; Rye, B. L.; Bennett, E. M.; Lander, N. S.; Macfarlane, T. D.; Western Australian Herbarium (1987). Flora of the Perth region. Part one. Western Australian Herbarium. Perth.