Australian Tropical Rainforest Orchids
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Trachoma speciosum

Showy Spectral Orchid

Trachoma speciosum D.L.Jones, B.Gray, M.A.Clem. & J.J.Wood, Austral. Orch. Res. 1: 145-146 (1989); Tuberolabium speciosum (D.L.Jones, B.Gray, M.A.Clem. & J.J.Wood) J.J.Wood, Nordic J. Bot. 10(5): 482 (1990); Parapteroceras speciosum (D.L.Jones, B.Gray, M.A.Clem. & J.J.Wood) Szlach., Ann. Bot. Fennici 40: 67 (2003). Type: cult. ANBG, 1985, M.A. Clements 3643 ex Queensland, Cook District, Leo Creek, McIlwraith Range, 26 July 1978, G. Butler 408 (holo CANB).

Distribution

Occurs in north-eastern Queensland on the Iron Range and McIlwraith Range.

Altitude: 300-600 m.

Also occurs in New Guinea.

Description

Epiphytic or lithophytic herb forming coarse upright clumps. Roots numerous, adherent, thick, cord-like, 0.3 cm wide, forming buttress supporting stem. Stems erect, 5-10 cm long, sparsely branched, thick. Leaves 4-8, scattered along stem, crowded, erect to prostrate, distichous, alternate, sessile, bases sheathing stem; lamina oblong to lanceolate, 8-14 cm x 2-2.5 cm, pale greyish green to yellow-green, thick, leathery, apex unequally emarginate. Inflorescence an axillary raceme, 20-45 mm long, rachis club-shaped, with sunken areas, bearing up to 15 flowers at once. Flowers numerous, resupinate, erect to porrect, 8-10 mm x 8-10 mm, short-lived, cream with orange and white labellum. Sepals and petals moderately spreading. Dorsal sepal erect, obovate, 7 mm x 2.5 mm, apex recurved. Lateral sepals free, divergent, obovate, 7 mm x 2 mm. Petals 7 mm x 1 mm. Labellum projected forwards, 6 mm x 4 mm, 3-lobed; lateral lobes short, more or less triangular, fleshy, curving outwards; midlobe 1 mm long, with short decurved spur. Column porrect, 2.5 mm long. Column foot absent. Capsules porrect, dehiscent.

Ecology

Occurs on trees along rainforest margins and in drier types of rainforests. It is also found on trunks and branches of large Hoop Pines (Araucaria cunninghamiana) which extend above the forest canopy. Large plants have a prominent buttress of thick white roots.

Highly localised.

Flowering period: December-May.

Name Changes

Until recently known as Tuberolabium speciosum.

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