Leptoceras (R.Br.) Lindl.
Edwards's Bot.Reg. pliii. (1839)

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

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

Family Orchidaceae.

Habit and leaf form. Colony-forming herbs (flowering after fire or disturbance). Perennial. Leaves basal. Tuberous. Helophytic, or mesophytic. Leaves medium-sized; ‘herbaceous’, or leathery, or fleshy; petiolate; simple. Leaf blades entire; flat; parallel-veined; cross-venulate, or without cross-venules. Leaf blade margins entire. Vernation conduplicate, or convolute. Leaf anatomy. Hairs absent (leaf smooth, shiny). Stem anatomy. Secondary thickening absent.

Reproductive type, pollination. Fertile flowers hermaphrodite. Unisexual flowers absent. Plants hermaphrodite. Floral nectaries present. Entomophilous (small native bees have been observed occasionally on the flowers). Pollination mechanism conspicuously specialized (the pollinators possibly initially attracted by the anther-like petals, then feeding on nectar at the base of the column (Hoffman & Brown 1992)).

Inflorescence and flower features. Flowers solitary; small to medium-sized; fragrant, or 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; red (lateral petals), or pink (adaxial sepal and labellum), or white (lateral sepals). Calyx (if the outer whorl be so designated) 3 (the median member ostensibly posterior); 1 -whorled; polysepalous. Corolla (i.e. the members of the inner whorl) 3; polypetalous; imbricate. Androecium 3, or 1 (by misinterpretation). Androecial members free of the perianth; united with the gynoecium (fused with the style to form a ‘gynostemium’); 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. 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 Australia, New South Wales, Victoria, and Tasmania. South-West Botanical Province.

Additional characters Perianth of 5 dissimilar members and the median inner member modified into the labellum (the lateral petals erect, ear-like, glandular; lateral sepals broader than the lateral petals; adaxial sepal hooded). Leaves solitary (occasionally 2; sheathing). Leaves erect. Labellum not insect-like. Perianth not glossy. Labellum with calli (calli stalked, in 2–4 rows).

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.