Diplocaulobium glabrum (J.J.Sm.) Kraenzl., Pflanzenreich Orch.-Mon.-Dendr. 45: 339 (1910).
Dendrobium glabrum J.J.Sm., Bull. Dept. Agric. Indes neerl. 5: 4 (1907). Type: Dutch New Guinea, Soengei, Meranke s.n. (holo BO).
Cadetia ruppii St.Cloud, North Queensland Naturalist 23(110): 2-3 (1955). Type: North Queensland; Whitfield Range, Cairns, Sep. 1934, S. St. Cloud s.n. (holo QRS).
Occurs in far north-eastern Queensland from Cape York to Whitfield Range near Cairns.
Altitude: 5-500 m.
Also occurs in Indonesia and New Guinea.
Epiphytic or lithophytic herb forming extensive spreading mats or spreading strands. Rhizome creeping, appressed to host, much-branched, 4-5 mm wide, sheathed in papery bracts. Pseudobulbs crowded, erect, ovoid, tapering toward apex, 4-5 cm x 1.2-1.5 cm, yellowish green, flattened, fleshy, shiny. Leaves solitary on pseudobulb, erect, apical, sessile; lamina ovate, 6-7.5 cm x 1-1.5 cm, leathery, green to yellowish, apex unequally acuminate. Inflorescence axillary, single-flowered, from perennial apical meristem on pseudobulb; pedicels 3 cm long, thin. Flower solitary, resupinate, erect to porrect, star-shaped, 20-25 mm x 20-25 mm, white with pale yellow tips, short-lived. Sepals and petals widely spreading, narrow, tapered. Dorsal sepal erect, narrowly triangular, 14-16 mm x 2.5 mm. Lateral sepals divergent, narrowly triangular, 14-16 mm x 1.5-2 mm, bases fused to column foot. Petals divergent, linear, 15-17 mm x 1 mm. Labellum curved, projecting forward, 8 mm x 3 mm, basal margins undulate, midlobe decurved with 2 converging ridges. Column 3 mm long. Column foot 3 mm long, at right-angles to column. Capsules porrect to pendulous, dehiscent.
Occurs in sparse rainforests and in open forest on humid slopes, where it forms large conspicuous yellowish green clumps on trees or rocks. Flowering occurs in spasmodic bursts with flowers opening at the same time in a massed event. Plants in the same area often flower simultaneously. The individual flowers last only 8-10 hours and are insect-pollinated.
Widespread and common.
Flowering period: Sporadic throughout the year.