Habenaria Willd.
Sp.Pl. Edn. 4, 4:5, 44 (1805)

Name Status: Current
Browse to the list of specimens for Habenaria Willd.

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

Family Orchidaceae.

Habit and leaf form. Herbs; deciduous. Perennial. Leaves basal, or cauline, or basal and cauline. Plants with a basal concentration of leaves, or with neither basal nor terminal concentrations of leaves; tuberous, or rhizomatous (rarely, rhizome very short). Helophytic, or mesophytic. Leaves medium-sized to large; alternate; scattered loosely up the stem; ‘herbaceous’, or leathery, or fleshy, or membranous; imbricate, or not imbricate; petiolate; simple. Leaf blades entire; flat; parallel-veined; cross-venulate, or without cross-venules; auriculate at the base, or cordate, or hastate, or sagittate, or attenuate at the base, or cuneate at the base, or oblique at the base, or rounded at the base. Leaf blade margins usually entire. Vernation convolute. Stem anatomy. Secondary thickening absent.

Reproductive type, pollination. Fertile flowers hermaphrodite. Unisexual flowers absent. Plants hermaphrodite. Entomophilous (species outside Australia known to be pollinated by moths and mosquitoes - pollinators of Australian species unknown). Pollination mechanism conspicuously specialized.

Inflorescence and flower features. Flowers aggregated in ‘inflorescences’, or solitary (very rarely). Inflorescence few-flowered to many-flowered. Flowers in spikes. The terminal inflorescence unit racemose. Inflorescences scapiflorous, or not scapiflorous; terminal. Flowers small to large; 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, or joined; white, or green, or yellow. 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; imbricate; (labellum deeply) spurred (at the base). 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 slender, erect with anther erect and firmly attached to apex, auricle usually present on each side of column); 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; usually elongated at base into caudicles, cells parallel or divergent at the base. 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; at base of the column, consisting of 2 narrow, outward and forward projecting parts (stigmaphores) which may be open along the bottom and adnate to the base of the labellum and the auricles, or cylindric and free but parallel to the auricles; 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 (adaxial sepal almost always erect, usually deeply concave; lateral petals either forming a galea with the adaxial sepal or slightly divergent; labellum usually deeply 3-lobed, occasionally entire; lobes strap-like or filiform). Leaves not solitary (2–11). Leaves more or less erect. Labellum not insect-like. Perianth not glossy.

Taxonomic Literature

  • Wheeler, J. R.; Rye, B. L.; Koch, B. L.; Wilson, A. J. G.; Western Australian Herbarium (1992). Flora of the Kimberley region. Western Australian Herbarium. Como, W.A.