Paracaleana Blaxell
Duck Orchids

Scientific Description

Family Orchidaceae.

Habit and leaf form. Slender herbs; deciduous. Plants succulent (stems fleshy), or non-succulent. Perennial. Leaves basal. Tuberous (tubers dark red, ovoid). Helophytic, or mesophytic. Leaves small to medium-sized; ‘herbaceous’, or leathery, or fleshy; petiolate; simple. Leaf blades entire; flat; linear to ovate; parallel-veined; cross-venulate, or without cross-venules; cordate. 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 (glands on the labellum emit pheromones which sexually attract the male wasps; when the insect lands on the glands the labellum flips over, causing the insect to touch one of the pollinia which becomes adhered to its back. When it attempts to mate with another flower an exchange of pollen takes place).

Inflorescence and flower features. Flowers solitary, or aggregated in ‘inflorescences’. Inflorescence several-flowered. Flowers in racemes (loose). The terminal inflorescence unit racemose. Inflorescences scapiflorous, or not scapiflorous; terminal; stem bracts absent. Flowers small to medium-sized; odourless; very irregular; zygomorphic; not resupinate (the labellum bent upward above the column). 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, or 7 (by misinterpretation); 2 -whorled; isomerous (but zygomorphic); free; green and red, or green and brown, or green and purple. Calyx (if the outer whorl be so designated) 3, or 5 (by misinterpretation); 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 tepals and column foot); united with the gynoecium (fused with the style to form a column or ‘gynostemium’; column the dominant feature of the flower, almost as long as the perianth segments, set at right angles to the ovary); coherent (via the gynostemium); 1 - adelphous; theoretically 2 -whorled. Androecium including staminodes, or exclusively of fertile stamens (by misinterpretation). Staminodes 2 (these anterior, supposedly the abaxial pair of the inner whorl). Stamens 1 (this across the flower from the labellum, i.e. anterior, 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. Not endemic to Australia. Australian states and territories: Western Australia, South Australia, Queensland, New South Wales, Victoria, Australian Capital Territory, and Tasmania. South-West Botanical Province.

Additional characters Perianth of 5 similar members and the median inner member modified into the labellum (adaxial sepal and lateral petals almost equal, linear, rather closely surrounding the column; lateral sepals similar to adaxial sepal but attached to the top of the column foot; labellum claw linear, long, curved, movable, attached to the top of the column foot; limb irritable, peltately attached, with a basal appendage or small lobe, ovate and beaked above, bearing calli). Leaves solitary. Leaves ground-hugging (usually). Column prominently winged (forming a pouch that almost encloses the stigma). Labellum insect-like. Labellum motile. Perianth not glossy.