Platysace Bunge
Pl.Preiss. 1(4):285 (1845)

Name Status: Current
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Scientific Description
H.R. Coleman, Thursday 8 September 2016

Family Apiaceae.

Habit and leaf form. Herbs; bearing essential oils, or without essential oils (?); resinous, or not resinous (?). Leaves well developed (often few or small, often withering early). Herbs perennial; plants with a basal concentration of leaves. Young stems terete, angular or flattened. Helophytic, or mesophytic. Leaves medium-sized to large; alternate; ‘herbaceous’; petiolate, or sessile; more or less sheathing. Leaf sheaths with free margins. Leaves gland-dotted, or not gland-dotted (?); aromatic, or foetid, or without marked odour (?); simple; pulvinate, or epulvinate (?). Leaf blades entire, or dissected; flat; linear, or ovate, or obovate, or oblong, or elliptic, or orbicular; when dissected, 3-lobed to greatly divided; pinnately veined, or palmately veined (?). Leaves without stipules; without a persistent basal meristem. Leaf anatomy. Hairs absent. Stem anatomy. Nodes multilacunar, or tri-lacunar (?). Secondary thickening developing from a conventional cambial ring, or anomalous (?); from a single cambial ring.

Reproductive type, pollination. Fertile flowers hermaphrodite, or hermaphrodite and functionally male. Unisexual flowers present, or absent. Plants hermaphrodite, or andromonoecious. Entomophilous.

Inflorescence and flower features. Flowers aggregated in ‘inflorescences’; in umbels. Inflorescences compound. The terminal inflorescence unit cymose, or racemose (?). Inflorescences terminal and axillary; irregular, usually pedunculate; rays few to many, sometimes reduced to simple pedicels; with involucral bracts. Flowers pedicellate; bracteate; small; regular; 5 merous (except for the gynoecium); cyclic; tetracyclic, or tricyclic. Free hypanthium absent. Perianth with distinct calyx and corolla (but the calyx greatly reduced), or petaline (apparently); 5, or 10; 2 -whorled, or 1 -whorled; white, or cream, or yellow. Calyx when detectable, 5; 1 -whorled; gamosepalous; more or less entire (reduced to a minute, inconspicuous rim); with the median member posterior. Corolla 5; 1 -whorled; polypetalous; valvate to imbricate; regular; white, or cream, or yellow. Petals ovate, or oblong. Corolla members entire (apex obtuse). Androecium 5. Androecial members free of the perianth; all equal; free of one another; 1 -whorled. Androecium exclusively of fertile stamens. Stamens 5; isomerous with the perianth; oppositisepalous; inflexed in bud. Anthers almost circular in outline; dehiscing via longitudinal slits; introrse; tetrasporangiate. Fertile gynoecium present, or absent (male flowers). Gynoecium 2 carpelled. The pistil 2 celled. Gynoecium syncarpous; synovarious; inferior. Ovary plurilocular; 2 locular. Gynoecium median. Epigynous disk present. Gynoecium stylate. Styles 2; free to partially joined (their bases thickened into a flat or conical stylopodium crowning the ovary); apical. Stigmas wet type; non-papillate; Group IV type. Placentation axile, or apical (?). Ovules 1 per locule, or 2 per locule (usually two, but one abortive ?); pendulous; epitropous; non-arillate; anatropous.

Fruit and seed features. Fruit non-fleshy; a schizocarp. Mericarps 2 (smooth or tuberculate, dorsal rib prominent or winged, intermediate ribs prominent or obscure). Seeds endospermic. Endosperm oily. Embryo well differentiated. Cotyledons 2. Embryo achlorophyllous; 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 Australia, Northern Territory, Queensland, New South Wales, Victoria, and Australian Capital Territory.

Additional characters Petals inflexed, or not inflexed (inflexed but at length spreading).

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.
  • 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.
  • Blackall, William E.; Grieve, Brian J. (1980). How to know Western Australian wildflowers : a key to the flora of the extratropical regions of Western Australia. Part IIIA. University of W.A. Press. Perth.