Eulophia R.Br.
Corduroy Orchids

Scientific Description

Family Orchidaceae.

Habit and leaf form. Herbs; evergreen, or deciduous. Leaves well developed (appearing after flowering), or absent. Autotrophic, or saprophytic (leafless species). Perennial; rhizomatous, or tuberous (large, subterranean, fleshy tuberous rhizomes or squat pseudobulbs). Self supporting, or epiphytic (rarely). Helophytic, or mesophytic, or xerophytic. Leaves very large; alternate, or opposite, or whorled; ‘herbaceous’, or leathery, or fleshy; imbricate, or not imbricate; petiolate; simple; jointed at the base of the blade. Leaf blades entire; flat; narrow and grass-like or broader; parallel-veined; cross-venulate, or without cross-venules. Leaf blade margins entire. Vernation plicate. Stem anatomy. Secondary thickening absent.

Reproductive type, pollination. Fertile flowers hermaphrodite. Unisexual flowers absent. Plants hermaphrodite. Entomophilous. Pollination mechanism conspicuously specialized.

Inflorescence and flower features. Flowers aggregated in ‘inflorescences’. Inflorescence few-flowered to many-flowered. Flowers in panicles, or in racemes (loose). The terminal inflorescence unit racemose. Inflorescences scapiflorous, or not scapiflorous; terminal, or axillary. Flowers pedicellate; 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; without spots, or spotted; green, or white to cream (with pink or purple markings). 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; (labellum) spurred (spur often small). Androecium 3, or 1 (by misinterpretation). Androecial members free of the perianth, or adnate (? via attachment of labellum to column foot); united with the gynoecium (fused with the style to form a column or ‘gynostemium’; column slender, the foot more or less developed); 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, often deeply cleft). 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, Northern Territory, and Queensland. Northern Botanical Province.

Additional characters Perianth of 5 similar members and the median inner member modified into the labellum, or of 5 dissimilar members and the median inner member modified into the labellum (sepals and lateral petals more or less equal, or petals slightly broader and shorter than sepals; labellum distinctly or indistinctly 3-lobed; lateral lobes erect and close to column; throat with 2 parallel keels which are usually short, sometimes ornamented with hairs and calli; midlobe often recurved, sometimes ornamented). Leaves solitary, or not solitary (then 2). Leaves erect. Column not prominently winged. Perianth not glossy.