Australian Tropical Rainforest Orchids

Arthrochilus irritabilis

Clubbed Elbow Orchid

Arthrochilus irritabilis F.Muell., Fragm. 1: 43 (1858); Drakaea irritabilis (F.Muell.) Rchb.f., Beitr. Syst. Pflanzenk. 68 (1871); Spiculaea irritabilis (F.Muell.) Schltr., Repert. Spec. Nov. Regni Veg. Beih. 17: 81 (1921). Type: Moreton Bay, W. Hill and F. Mueller s.n. (holo MEL; iso K-LINDL).


Occurs in Queensland from Ingham to Brisbane.

Altitude: 0-350 m.


Terrestrial tuberous herb forming spreading colonies. Sterile and flowering plants dimorphic.Sterile plants a basal rosette of leaves only. Fertile plants an inflorescence with a rosette arising later from lateral stem at base of peduncle. Leaves 3-5, prostrate, ground-hugging, basal; lamina narrowly lanceolate, 3-8 cm x 0.8-1.4 cm, bluish green. Inflorescence a terminal raceme, erect, 120-350 mm long. Flowers 5-30, non-resupinate, erect to porrect, 10-14 mm long, light greenish or reddish with reddish or purplish labellum glands. Dorsal sepal free, decurved, 8-11 mm x 2 mm, base embracing proximal third of column, conduplicate in distal half, apex obtuse. Lateral sepals reflexed against the ovary, oblong, falcate, 5-7 mm x 1-1.5 mm, distal margins conduplicate, apex obtuse. Petals reflexed against the ovary, linear, 5-7 mm x 1 mm. Labellum free, 5 mm x 1 mm, hinged to underside of column foot by claw, base reddish, 1.5 mm wide. Callus insectiform, proximally fused to lamina, 2.5 mm long; central area with crowded, clubbed calli, 0.5-1.5 mm long, reddish or purplish; apex 1 mm wide, emarginate, with shiny blackish glands. Column incurved in a semi-circle, with 2 pairs of column wings; proximal column wings projecting forwards, triangular; distal wings smaller, narrowly triangular, divergent above anther. Column foot 4 mm long. Capsules not seen.


Occurs in coastal areas in forests, woodlands, Wallum and heathlands, growing in well-drained soil, where it often forms large colonies. It flowers for extended periods during the rainy season.

Widespread and common.

Flowering period: November-February.

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