Australian Tropical Rainforest Orchids
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Didymoplexis pallens

Crystal Bells

Didymoplexis pallens Griffith, Calcutta J. Nat. Hist. 4: 383, t. 17 (1843); Epiphanes pallens (Griffith) Rchb.f. in Seem., Fl. Vitensis 296 (1868); Gastrodia pallens (Griffith)F.Muell., Contr. phytogr. New Hebrides 22 (1870). Type: India; Prope caespites Bambusarum, Calcutta, Serampore, W. Griffith s.n. (holo CAL).

Arethusa bengalensis Hort. ex Hemsley, J. Proc. Linn. Soc., Bot. 20: 311 (1884), pro. syn.

Leucorchis sylvatica Blume, Mus. Bot. 1:31 (1849); Didymoplexis sylvatica (Blume) Ridl., J. Bot. 345 (1884). Type: In provincia Bantam Javae insulae, Harriang s.n. (holo not found; iso BM).

Apetalum minutum Wight, Icon. Pl. Ind. Orient 5(1): 22, t. 1758 (1851). Type: India, Wight? (holo K).

Arethusa ecristata Griffith in McCelland, Post. Pap. Griff. 3: 378 (1851). Type: (icon t. 343, Icon. Pl. Asia. (1847) ).

Pogonia pachystomoides F.Muell., Fragm. 8: 174 (1874); Nervilia pachystomoides (F.Muell.) Schltr., Bot. Jahrb. Syst. 45: 404 (1911); Didymoplexis pachystomoides (F.Muell.) Garay & Kittr., Bot. Mus. Leafl. 30(3): 48 (1985). Type: Ad sinum Rockingham’s Bay, W. Hill s.n. (holo MEL).

Cheirostylis kanarensis Blatt. & McCann, J. Bombay Nat. Hist. Soc. 35: 732-3, f. 4 (1932). Type: N. Kanara: Tatwal, June 1912, T.R. Bell s.n. (not found).

Distribution

Occurs in Western Australia in the Kimberley region and in the northern mainland of the Northern Territory. In north-eastern Queensland it occurs on some Torres Strait islands, and from Cape York to Cardwell.

Altitude: 0-450 m.

Also occurs on Christmas Island, India, Indonesia, Malaysia, Myanmar, New Guinea and Thailand.

Description

Leafless terrestrial herb. Rhizomes tuberous, horizontal, irregularly shaped, up to 8 mm long, fleshy. Inflorescence a terminal raceme, erect, 60-120 mm tall, whitish or yellowish, fleshy, brittle; pedicels 5 mm long; stem and pedicels elongating in fruit. Flowers 5-15, resupinate, porrect to semi-erect, campanulate, 6-8 mm x 8-10 mm, crystalline white, sometimes with brown markings, short-lived, opening singly in succession up the raceme. Sepals and petals similar, fused in basal half forming a campanulate tube, upper parts free, not opening widely. Dorsal sepal incurved, oblong, apex obtuse. Lateral petals recurved, apex obtuse. Labellum cuneate, 6-7 mm x 9-10 mm; margins incurved and hugging column; apex often emarginate or lobed. Calli cream to yellow, arranged centrally in 2-3 irregular rows. Column 4-6 mm long. Column foot curved, 1-2 mm long. Capsules erect, dehiscent.

Ecology

Occurs in rainforests, bamboo groves and grassy forests, sometimes growing within grass tussocks. Plants are above ground for only 3-5 weeks, appearing with the first rains of the wet season. They are small and easily overlooked and may occur more commonly than records suggest. The flowers open singly, lasting less than a day and are insect-pollinated. The flowering stem elongates as the fruit develops and plants are more visible when in fruit.

Highly localised.

Flowering period: November-March.

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