Spiculaea Lindl.
Edwards's Bot.Reg. plvi. (1839)

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

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

Family Orchidaceae.

Habit and leaf form. Herbs. Plants succulent (upper part of flowering stem fleshy). Perennial. Leaves basal (sheathing the base of the stem, withering before flowering complete). Tuberous (tubers rounded). Helophytic, or mesophytic. Leaves small to medium-sized; ‘herbaceous’, or leathery, or fleshy; petiolate; simple. Leaf blades entire; flat; ovate; parallel-veined; cross-venulate, or without cross-venules. Leaf blade margins entire. Vernation conduplicate. Leaf anatomy. Hairs absent. Stem anatomy. Secondary thickening absent.

Reproductive type, pollination. Fertile flowers hermaphrodite. Unisexual flowers absent. Plants hermaphrodite. Entomophilous (Thynnid wasps). Pollination mechanism conspicuously specialized (the flower emits a pheromone that sexually attracts the male wasps; when the male attempts to fly off with the ‘female’ it is bought in contact with the column, and momentarily held to it by the ‘mantis-like’ wings).

Inflorescence and flower features. Flowers aggregated in ‘inflorescences’. Inflorescence few-flowered. Flowers in racemes (loose). The terminal inflorescence unit racemose. Inflorescences scapiflorous, or not scapiflorous; terminal; stem bract 1, near middle of stem. Flowers 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; yellow, or brown. 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 column or ‘gynostemium’; column elongate, narrow, incurved); 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-West Botanical Province.

Additional characters Perianth of 5 similar members and the median inner member modified into the labellum (sepals and lateral petals very narrow; adaxial sepal erect and incurved, other segments reflexed or spreading; labellum articulate near the base and movable, pendulous, with a long narrow claw; limb peltately attached, hammer-shaped with a narrow projection at the lower end and a reflexed point under the apex, ornamented with a fleshy callus fringed with glandular hairs). Leaves solitary. Column prominently winged (forming narrow projections). Labellum insect-like. Labellum motile. Perianth not glossy.

Taxonomic Literature

  • Hopper, Stephen D.; Brown, Andrew P. (2001). Contributions to Western Australian orchidology. 1, history of early collections, taxonomic concepts and key to genera.
  • Brown, Andrew; Hoffman, Noel (1995). Orchids of south-west Australia. University of W.A. Press. Nedlands, W.A.