Australian Tropical Rainforest Orchids

Plectorrhiza tridentata

Common Tangle Orchid

Plectorrhiza tridentata (Lindl.) Dockrill, Austral. Sarcanth. 27, t. 14 (1967).

Cleisostoma tridentata Edwards’s, Bot. Reg. 24: Misc. 33 (1838); Sarcochilus tridentatus (Lindl.) Rchb.f. in Walp., Ann. Bot. Syst. 6: 500 (1861); Thrixspermum tridentatum (Lindl.) Rchb.f., Xenia Orchid. 2: 122 (1874); Sarcanthus tridentatum (Lindl.) Rupp, Victorian Naturalist 57: 218 (1941); Thrixspermum tridentatum (Lindl.) T.E.Hunt, Queensland Naturalist 16: 27 (1958), nom. illeg. Type: NewHolland, Loddiges s.n. (holo K-LINDL).

Saccolabium calcaratum F.Muell., Fragm. 1: 192 (1859); Sarcochilus calcaratus (F.Muell.) F.Muell., Fragm. 2: 181, 194 (1861). Type: In silvis circum Moreton Bay, Oct.-Nov., W. Hill s.n. (holo MEL).

Cleisostoma cornutum Rupp, North Queensland Naturalist 57: 218 (1941). Type: ?Bellenden Ker Range, 1935, H. Flecker s.n. (holo NSW).


Occurs in Queensland from Mount Windsor Tableland to far eastern Victoria.

Altitude: 0-1000 m.


Epiphytic or lithophytic herb forming straggling clumps. Plants usually with single main growth suspended by one to few roots. Roots coarse, appressed to host when young, tangled and pedulous when older. Stem erect to pendulous, 10-30 cm long, flattened. Leaves 5-20, scattered along the stem, well-spaced, prostrate, distichous, alternate, sessile, bases sheathing stem; lamina narrowly ovate, 5-10 cm x 1-1.5 cm, green or purplish, apex acute to acuminate. Inflorescence an axillary raceme, 50-120 mm long, pendulous; pedicels 6 mm long, including ovary. Flowers 3-15, resupinate, porrect to nodding, star-shaped, 5-6 mm x 6-8 mm, green or brown with prominent white labellum. Sepals and petals widely spreading, oblong to ovate, apices acuminate. Dorsal sepal incurved to erect, 4-5 mm x 2 mm. Lateral sepals free, 6-7 mm x 2 mm. Petals 4-5 mm x 1.5 mm. Labellum 6-7 mm x 4 mm, projected forwards, white with green basal patch, 3-lobed; lateral lobes 2 mm x 2 mm, nearly triangular, covering midlobe; midlobe 2 mm long, blunt; spur 3 mm long, curved. Column 2.5 mm long. Column foot 0.5 mm long, in line with column. Capsules porrect, dehiscent.


Occurs in rainforests in humid areas such as steep gullies, protected slopes and swamps, where it grows on trees and on the outer twigs of rainforest trees. The plants are supported by very few roots even when large, and the majority of roots grow through the air forming a tangled mass. The flowers are attractively scented.

Widespread and common.

Flowering period: September-January.

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