Drakaea Lindl.
Edwards's Bot.Reg. plv. (1839)

Name Status: Current
Browse to the list of specimens for Drakaea Lindl.

Scientific Description
H.R. Coleman, Thursday 8 September 2016

Family Orchidaceae.

Habit and leaf form. Herbs (forming loose, scattered colonies). Plants succulent (leaf fleshy). Perennial. Leaves basal. Young stems wiry, the basal part reddish and narrower than the central part. Tuberous (tuber rounded, succulent). Helophytic, or mesophytic. Leaves small to medium-sized; fleshy; petiolate; simple. Leaf blades entire; flat; ovate; parallel-veined; cross-venulate, or without cross-venules; cordate. Leaf blade margins entire. Vernation conduplicate. Leaf anatomy. Hairs absent (usually), or present. Stem anatomy. Secondary thickening absent.

Reproductive type, pollination. Fertile flowers hermaphrodite. Unisexual flowers absent. Plants hermaphrodite. Entomophilous (Thynnid wasps). Pollination mechanism conspicuously specialized (via pseudo-copulation: the flowers emit a scent similar to that of the female Thynnid wasp and the labellum visually resembles a wingless female at the top of a grass stem - the male wasp grabs the labellum and, in an attempt to fly away with it, can move freely only in one direction, thus bringing itself into contact with the column).

Inflorescence and flower features. Flowers solitary. Inflorescences stem bract 1, below the middle of the stem, closely sheathing. Flowers pedicellate; small to medium-sized; odourless; very irregular; zygomorphic; resupinate. The floral asymmetry involving the perianth and involving the androecium. Flowers 3 merous; cyclic; supposedly basically pentacyclic. Perigone tube absent. Perianth of ‘tepals’, or with distinct calyx and corolla; 6; 2 -whorled; isomerous (but zygomorphic); free. Calyx (if the outer whorl be so designated) 3; 1 -whorled; polysepalous. Corolla (i.e. the members of the inner whorl) 3; polypetalous; imbricate. Androecium 3, or 1 (by misinterpretation). Androecial members adnate (via fusion of labellum claw and base of the column); united with the gynoecium (fused with the style to form a column or ‘gynostemium’; column abruptly incurved near the middle, with a long, linear basal claw); coherent (via the gynostemium); 1 - adelphous; theoretically 2 -whorled. Androecium including staminodes, or exclusively of fertile stamens (by misinterpretation). Staminodes 2 (these anterior (ostensibly posterior), supposedly the abaxial pair of the inner whorl). Stamens 1 (this across the flower from the labellum, i.e. anterior but ostensibly posterior, supposedly representing the outer whorl); reduced in number relative to the adjacent perianth; alterniperianthial (i.e. with reference to the single stamen, across the flower from the labellum); filantherous, or with sessile anthers. Anthers dorsifixed to basifixed; dehiscing via longitudinal slits; introrse; tetrasporangiate; appendaged, or unappendaged. Pollen shed in aggregates; in the form of pollinia (pollinia 2). Gynoecium 3 carpelled. The pistil 1 celled. Carpels isomerous with the perianth. Gynoecium syncarpous; eu-syncarpous; inferior. Ovary unilocular; 1 locular. The ‘odd’ carpel anterior (away from the labellum). Gynoecium stylate. Styles 1 (inflexed); apical. Stigmas 1; 3 - lobed (but becoming much modified in form, the apex of the median lobe forming the ‘rostellum’); wet type; papillate; Group III type. Placentation parietal. Ovules not differentiated; in the single cavity 30–100 (i.e. very numerous); non-arillate; anatropous.

Fruit and seed features. Fruit non-fleshy; dehiscent; a capsule. Capsules septicidal, or loculicidal. Fruit 30–500 seeded (i.e. seeds usually very numerous). Seeds endospermic (endosperm development arrested very early), or non-endospermic; minute; without starch. Embryo rudimentary at the time of seed release, or weakly differentiated. Seedling. Seedling collar not conspicuous. Primary root ephemeral.

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

Additional characters Perianth of 5 similar members and the median inner member modified into the labellum (sepals and lateral petals almost equal in length, narrowly linear; adaxial sepal erect, other perianth segments reflexed downwards, usually against the ovary; labellum widely separated from the other segments, with a long narrow claw arising almost perpendicularly from the basal claw of the column; limb mobile, peltately attached to the claw, unequally 2-lobed, broad, partially hairy and partially glandular). Leaves solitary. Leaves ground-hugging. Column prominently winged (at the base). Labellum highly insect-like. Labellum motile. Perianth not glossy.

Taxonomic Literature

  • Wheeler, Judy; Marchant, Neville; Lewington, Margaret; Graham, Lorraine (2002). Flora of the south west, Bunbury, Augusta, Denmark. Volume 1, introduction, keys, ferns to monocotyledons. Australian Biological Resources Study. Canberra.
  • Hopper, Stephen D.; Brown, Andrew P. (2001). Contributions to Western Australian orchidology. 1, history of early collections, taxonomic concepts and key to genera [electronic resource].
  • Brown, Andrew; Hoffman, Noel (1995). Orchids of south-west Australia. University of W.A. Press. Nedlands, W.A.
  • (1988-). Australian systematic botany. CSIRO. East Melbourne, Vic.