Durabaculum undulatum M.A.Clem. & D.L.Jones var. undulatum Orchadian 13(11): 489 (2002).
Dendrobium undulatum R.Br., Prod. 332 (1810), non Pers. (1807); Callista undulata (R.Br.) Kuntze, Revis. gen. pl. 2: 655 (1891). Type: (T.) v.v. [Keppel Bay, Port Bowen, 1802, R. Brown s.n.] (holo BM; iso E, K-LINDL, MEL).
Dendrobium elobatum Rupp, Victorian Naturalist 69: 116-7 (1953). Type: Growing on Wormia alata in the mangrove scrubs of Trinity Bay, Cairns district, N. Queensland, Aug. 1952, S.F. Goeswsling-St. Cloud s.n. (holo NSW).
Occurs in Queensland on some Torres Strait islands, and from Cape York to Rockhampton, including islands along the coast.
Altitude: 0-500 m.
Epiphytic or lithophytic herb forming large clumps. Pseudobulbs erect to arching, elongate, cylindrical, slightly thicker in middle, 100-500 cm x 4-6 cm, green, becoming yellowish, sometimes striped, hard, covered in papery bracts when young. Leaves 10-35, scattered along upper two-thirds of stem, erect to prostrate, distichous, sessile, bases sheathing stem; lamina ovate, 8-16 cm x 3.5-5 cm, dark green to yellowish, often concave, leathery, apex emarginate. Inflorescence an axillary raceme, erect to arching, 20-60 cm long. Flowers 10-40, resupinate, porrect, opening sequentially, star-shaped, 40-80 mm x 40-80 mm, mainly light brown to dark brown but also yellow, yellowish brown, bronze, often with mauve to purple markings on labellum. Sepals and petals widely spreading, strongly twisted, with undulate margins. Dorsal sepal recurved, narrowly oblong, 25-35 mm x 5-7 mm. Lateral sepals widely divergent, narrowly oblong to narrowly triangular, 25-35 mm x 5-7 mm bases fused to column foot. Petals obliquely erect, narrowly oblong to narrowly obovate, 35-40 mm x 7-8 mm. Labellum 17-24 mm x 11-15 mm, 3-lobed; lateral lobes, large, outcurved; midlobe decurved, 5-7 mm x 2-4 mm, with 3 main ridges, sometimes also accessory ridges, margins undulate. Column 3-6 mm. Column foot 5-12 mm. Capsules porrect to pendulous, dehiscent.
Occurs in a wide range of habitats in coastal regions and adjacent ranges including sparse rainforests, rainforest margins, open forests, woodlands, coastal scrubs, scrubby thickets, mangroves and remnant trees in paddocks. It usually grows in exposed situations on trees and rocks, but also on coastal headlands, coral accumulations and sometimes in beach sand. It spreads vegetatively through numerous aerial growths that eventually become separate plants. The long-lasting flowers are extremely variable in size and colour and this is a popular garden plant in the tropics.
Widespread and common.
Flowering period: August-November.
Until recently known as Dendrobium undulatum or Dendrobium discolor.