Australian Tropical Rainforest Orchids
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Arthrochilus corinnae

Swamp Elbow Orchid

Arthrochilus corinnae D.L.Jones, Orchadian 14(8): Suppl. iii-iv (June 2004). Type: Queensland: Cook District; Swamp on south bank of Dulhunty River, Old Telegraph Road crossing, Cape York Peninsula, 23 Jan. 1992, D.L. Jones 8888 and C.H. Broers (CBG 9220175) (holo CANB; iso BRI, MEL).

Distribution

Occurs in far north-eastern Queensland on Northern Cape York Peninsula.

Altitude: 20-100 m.

Description

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 2-3, prostrate, ground-hugging, basal; lamina narrowly ovate to narrowly lanceolate, 2-25 mm x 3-7 mm, dull bluish green above, shiny beneath, apex acute to acuminate. Inflorescence a terminal raceme, erect, 150-300 mm tall, slender, green; pedicels obliquely erect, c. 2 mm long. Flowers 3-12, non-resupinate, erect to porrect, 9-14 mm long, pale green with shiny yellow labellum glands. Dorsal sepal free, decurved, linear-obovate when flattened, 8-10 mm x 2.4 mm base embracing proximal third of column, conduplicate in distal half, apex obtuse. Lateral sepals reflexed against the ovary, oblong, falcate, 5-6.5 mm x 2 mm, distal margins conduplicate, apex obtuse. Petals reflexed against the ovary, linear, falcate, 6-7 mm x 1 mm, apex obtuse to subacute. Labellum free, recurved, 5.5 mm x 0.8 mm, hinged to underside of column foot by claw 0.1 mm long, base dark purple, 1.4 mm wide, becoming pale green along the lamina, apex obtuse. Callus insectiform, proximally fused to lamina, 4 mm long; central area with crowded shiny clubbed calli 0.6-1 mm long; apex broadly emarginate, 1.6 mm wide, with shiny black glands. Column incurved in a semi-circle, 7 mm long, inner surface shortly pubescent, with 2 pairs of column wings; proximal column wings projecting forwards, triangular, 3 mm x 3 mm; distal wings smaller, narrowly triangular, 2 mm x 0.4 mm, divergent above anther. Column foot 2 mm long, apex anvil-shaped. Capsules not seen.

Ecology

Occurs in seasonally inundated, low-lying swampy habitats. It typically grows in dark grey to blackish sandy loams in areas dominated by species of Melaleuca and Pandanus.

Highly localised.

Flowering period: November-February.

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