Australian Tropical Rainforest Orchids
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Chiloschista phyllorhiza

White Starfish Orchid

Chiloschista phyllorhiza (F.Muell.) Schltr., Bot. Jahrb. Syst. 56: 492 (1921).

Sarcochilus phyllorhizus F.Muell., Fragm. 5: 201 (1866); Thrixspermum phyllorhizum Rchb.f., Beitr. Syst. Pflanzenk. 71 (1871). Type: Ad promontorium Cape York, E. Daemel s.n. (holo MEL; iso W).

Distribution

Occurs in the northern parts of Northern Territory and in  Queensland where it occurs on some Torres Strait islands, and in the north-east from Cape York Peninsula to the Tully River.

Altitude: 0-200 m.

Also occurs in Indonesia and New Guinea.

Description

Leafless epiphytic or lithophytic herb forming small clumps. Roots numerous, radiating, flattened, 10-20 cm x 0.6-0.1 cm, grey-green to dark green, roughened. Stems inconspicuous, less than 0.5 cm long. Leaves absent. Inflorescence an axillary raceme, arching, 50-150 mm long, thin, rigid, bearing flowers in spasmodic bursts. Flowers numerous, resupinate, erect to porrect, star-shaped, 10-14 mm x 10-14 mm, crystalline white with yellow labellum. Sepals and petals widely spreading. Dorsal sepal free, erect, obovate to ovate, 4-6 mm x 3-4 mm. Lateral sepals similar to dorsal sepal, divergent, 4-6 mm x 3-4 mm, bases fused to column foot. Petals ovate, 4-5 mm x 3-4 mm. Labellum dissilimar to sepals and petals, 2.5 mm long, hinged to apex of column foot, 3-lobed; lateral lobes 2 mm long, erect; midlobe 1 mm long, incurved, fleshy, yellow, densely hairy. Column 1.5 mm long. Column foot 2 mm long, at right-angles to column. Both column and column foot with reddish-purple markings on inner surface. Capsules porrect, dehiscent.

Ecology

Occurs in rainforest margins and on sheltered ridges and slopes growing on trees in swamps and streamside vegetation. The roots shine when wet but these plants are generally inconspicuous and easily overlooked. The flowers last for one to two days, sometimes closing at night and reopening the next day, and are pleasantly fragrant. Flowering occurs in sporadic bursts, with plants in the same area flowering simultaneously.

Locally common.

Flowering period: November-February.

Notes

This leafless plant has flat green roots which contain chlorophyll and are photosynthetic.

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