Erect to pendulous epiphytes or lithophytes with thick roots and long relatively thick fibrous leafy stems. The well-spaced, relatively large, thick, leathery leaves are arranged in 2 ranks. Inflorescences are few-flowered clusters arising from the nodes. The flowers, which last a few days, are produced spasmodically throughout the year. They have thick-textured segments and a stiffly attached labellum which has a deeply pouched basal spur with a narrow internal structure that is attached to the rear wall and extends forwards over the opening to the spur. The column is short and lacks a column foot.
Significant Generic Characters
Epiphytic/lithophytic orchids; plants large, rarely climbing; roots thick; stems fibrous; leaves well-spaced, in 2 ranks, much longer than wide, thick, leathery, unequally notched; inflorescence greatly reduced; flowers in nodal clusters, lasting a few days, produced spasmodically; perianth segments thick-textured; sepals subsimilar; petals slightly smaller than the sepals; labellum firmly attached to the base of the column; lamina 3-lobed, with a basal spur; bases of lateral lobes free or fused to basal margins of the column; spur deeply saccate, with a single narrow callus structure attached to the posterior wall and extending across the orifice; callus pubescent; column short, lacking a foot; pollinia 4, sessile on a stipe, in 2 unequal pairs.
Size and Distribution
A genus of about 60 species distributed in Asia, South-east Asia, Malesia, Melanesia, including New Guinea, and Australia where there is a single endemic species, Trichoglottis australiensis, restricted to the Iron Range (12°38’ S) and McIlwraith Range (about 13º34’ S) on Cape York Peninsula in northeastern Queensland. State occurrence: Queensland.
Ecology
Trichoglottis australiensis grows on rocks and trees in rainforest at low to moderate altitudes. It favours slopes and gullies in drier rainforest but also occurs in dense vegetation along streams. The climate is tropical and the majority of rain falls during the summer wet season (December to March), with the remaining months much drier and having sporadic or intermittent rain.
Biology
Pollination: The flowers of Trichoglottis species are produced in clusters, last a few days and are probably pollinated by native bees.
Reproduction: Reproduction in Trichoglottis is solely from seed. Seed dispersal takes 10-12 months after pollination and the capsules develop in a porrect to pendulous position. Apomixis is unknown in the genus.
Seasonal Growth: Plants of Trichoglottis species grow mainly during the spring and summer months and are relatively quiescent for the remainder of the year.
Flowering: Trichoglottis australiensis flowers spasmodically throughout spring and summer.
Hybrids: Natural hybrids involving Trichoglottis australiensis are unknown.
Derivation
Trichoglottis, which is derived from the Greek thrix, tricho, hair and glotta, tongue, refers to the pubescent labellum in the type species.
Botanical Description
Perennial, evergreen, epiphytic or lithophytic herbs, monopodial. Roots thick, elongate, mainly adherent. Plants mostly large, sparsely branched from the base, erect, porrect or pendulous, rarely climbing. Stem relatively thick, long, fibrous, leafy throughout. Pseudobulbs absent. Trichomes present on the labellum. Leaves lasting several seasons, distichous, sessile, relatively large, much longer than wide, flat, thick, coriaceous, smooth; base sheathing the stem, usually imbricate with its neighbour, persistent after leaf abscission; margins entire; apex unequally emarginate. Inflorescence lateral, consisting of reduced nodal racemes bearing 1-few flowers in a cluster. Peduncle greatly reduced, with imbricate scarious bracts. Rhachis greatly reduced. Floral bracts scarious, sheathing the base of the pedicel. Pedicel short to relatively long, thin, merging with the ovary. Ovary short, mostly straight. Flowers resupinate, relatively small to large, stalked, opening simultaneously, lasting a few days, cream to yellowish or brownish, often with colour patterns. Perianth segments relatively thick-textured, spreading. Dorsal sepal free, subsimilar to the lateral sepals. Lateral sepals free, subsimilar to the dorsal sepal, flanking the labellum. Petals free, slightly shorter than the sepals. Labellum stiffly attached to the base of the column, the basal margins of the lateral lobes fused to the lower margins of the column, markedly dissimilar in size and shape to the sepals and petals, calcarate. Labellum lamina fleshy, with a basal spur, 3-lobed; spur deeply saccate, widening distally, with a narrow strap-like structure attached to the proximal wall and extending across the orifice, sometimes a tooth like ridge also present on the distal wall; lateral lobes small, free or the basal margins fused to the lower margins of the column; mid-lobe well-developed, porrect, thick, fleshy, entire or trilobed. Spur (see labellum). Callus thickened, pubescent. Nectar unknown. Column short, porrect from the apex of the ovary, lacking free filament and style, fleshy, nearly straight. Column wings present, as small apical teeth. Column foot absent (perhaps sometimes vestigial). Pseudospur absent. Anther terminal, incumbent, 2-celled, persistent, smooth, with a narrow entire or emarginate rostrum. Pollinarium present. Pollinia 4 in 2 appressed pairs, unequal, orange, hard, waxy, sessile. Stipe well-developed, narrow with revolute margins. Viscidium present, small, at an angle to the stipe. Rostellum ventral, bifid. Stigma entire, concave. Capsules dehiscent, glabrous, porrect; peduncle not elongated in fruit; pedicel not elongated in fruit. Seeds numerous, light coloured, winged.
Taxonomy
Within the Vandeae, Trichoglottis is distinguished by the thick roots, long leafy stems, flowers lasting a few days, produced at spasmodic intervals and arising in nodal clusters, bases of the labellum lateral lobes free or fused to basal margins of the column, the labellum spur containing a single narrow callus structure attached to the posterior margin and extending over the opening to the spur, column short, lacking a foot and, 4 sessile pollinia in 2 unequal pairs.
Nomenclature
Trichoglottis Blume, Bijdr. 6: t.3 (1825). Type species: Trichoglottis retusa Blume.
Infrageneric Taxa: No infrageneric taxa are currently recognised.
References
Dockrill, A.W. (1967). Australasian Sarcanthinae. The Australasian Native Orchid Society, Sydney.
Dockrill, A.W. (1969). Australian Indigenous Orchids. Volume 1. The Society for Growing Australian Plants, Halstead Press, Sydney.
Dockrill, A.W. (1992). Australian Indigenous Orchids. Volume 1 & 2. Surrey Beatty & Sons in association with The Society for Growing Australian Plants, Chipping Norton, NSW.