Australian Tropical Rainforest Orchids
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Dendrobium stuartii

Fringed Tree Orchid

Dendrobium stuartii F.M.Bailey, Proc. Roy. Soc. Queensland 1: 12 (1884); Callista stuartii (F.M.Bailey) Kuntze, Revis. gen. pl. 2: 655 (1891). Type: cult. Brisbane Botanic Gardens ex Herberton, J.W.R. Stuart s.n. (holo BRI not found; neotype Fitzgerald’s illustration of Dendrobium stuartii in Aust. orch. 2(3): [t. 6] (1888) CANB), fide Clements (1989).

Dendrobium whiteanum T.E.Hunt, Queensland Naturalist 14: 60 (1951). Type: cult. Brisbane, 31 Jan. 1950, T.E. Hunt 181 ex Queensland-Cook District: Portland Roads, A. Johnson s.n. (holo BRI).

Distribution

Occurs in far north-eastern Queensland from Bamaga to the McIlwraith Range.

Altitude: 50-350 m.

Also occurs in Indonesia and New Guinea.

Description

Epiphytic or lithophytic herb with forming small pendulous clumps. Pseudobulbs slender, pendulous, subcylindrical, 10-60 cm x 0.4-0.5 cm, moderately zig-zagged, green to yellowish, leafy when young and covered in papery bracts, denuded when older. Leaves scattered along pseudobulb, erect to prostrate, alternate, distichous, sessile; lamina asymmetrically ovate, 5-8 cm x 2-2.5 cm, thin-textured, pale green, apex acuminate. Inflorescence an axillary raceme, drooping to pendulous, 15-25 mm long, from lateral nodes on pseudobulb, slender; pedicels 15-20 mm long, filiform. Flowers 1-3, resupinate, porrect to nodding, star-shaped, 12-15 mm x 15-20 mm, whitish to lime green, yellowing with age, opening reluctantly to freely. Dorsal sepal recurved, narrowly triangular, 12-15 mm x 4 mm. Lateral sepals divergent, recurved, narrowly triangular, 12-15 mm x 4 mm, bases fused to column foot. Petals spreading, narrowly ovate to elliptic, 12-15 mm x 4 mm, apex obtuse. Labellum projected forwards, 18 mm x 12 mm, white with mauve veins; inrolled and tubular toward base; distal part flared with hairy margins and 3 hairy ridges. Column 6 mm long. Column foot 3.5 mm long, in line with column. Capsules pendulous, dehiscent.

Ecology

Occurs in rainforests at low to moderate altitudes growing on trees. The new growths emerge at the start of the rainy season and the leaves are held for the summer only, being shed at start of dry season. The leafless plants are particularly inconspicuous. The flowers are short-lived and self-pollinating, and on some plants barely open.

Localised.

Flowering period: December-March.

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