Dendrobium cyanocentrum

Dendrobium cyanocentrum Schltr., in K.Schum. & Lauterb., Nachtr. Fl. Deutsch. Schutzgeb. Südsee (1905) 160; Repert. Spec. Nov. Regni Veg. Beih. 21 (1923) t. 178, fig. 665.

Type: Schlechter 13930 (holo B, lost; iso BM, BR, K, P).

Erect to semi-pendulous tufted epiphyte, 1.5-8 cm high, often forming clumps to 12 cm across. Roots 0.4-1 mm diameter. Rhizome short, to c. 3 mm long. Pseudobulbs 0.3-2.5 by 0.15-0.4 cm, ovoid, obclavate to cylindrical, greenish or greenish yellow or reddish, 2-3(-4)-leaved at apex. Leaves 1-6 by 0.1-0.3 cm, erect to spreading, linear-subulate, flat to shallowly V-shaped in section, pale yellowish green to dark green above, paler, sometimes purplish red below, apex acute to subacuminate, sometimes apiculate or obliquely pointed; sheaths pale green, membranous, with age becoming fibrous. Inflorescences terminal from leafy or leafless pseudobulbs, 1(-2)-flowered, subsessile; bracts c.3.5 by 2.7 mm, ovate-acuminate, usually enclosing mentum apex. Flowers 1.1-1.8 cm (measured to tip of dorsal sepal in erect position), sepals and petals usually strongly reflexed and with age often bent back parallel to pedicel and ovary. Median sepal 5-7.5 by 2-3 mm, lanceolate to narrowly ovate or ovate-triangular, strongly acuminate-subulate, becoming strongly reflexed and often convex. Lateral sepals 10.5-17 by 2-3 mm, ovate-triangular, strongly acuminate-subulate, usually strongly reflexed; basal fused part 1.5-3 mm, subconical; mentum total length 5.5-l0 mm, tip obtuse to shortly bilobed, usually enclosed by bract. Petals 4-6.5 by 1.5-3 mm narrowly ovate-triangular to obovate, occasionally linear-ligulate, usually reflexed. Lip 10-14 by 1.5-2.5 mm, linear-lanceolate, subtrilobate, adnate to column foot at base, apical part with margins only slightly incurved, transverse callus present, V-shaped or M-shaped or emarginate, apex of lip narrowly triangular acuminate or cuspidate, usually straight or sometimes slightly deflexed. Column 1.5-2 mm long; foot 5.5-10 mm long; anther 1.5-2.5 mm broad; pollinia 0.6-l mm long. Ovary 3-winged to triangular in cross-section; pedicel and ovary 7-15 mm long. Fruit 12 by 7 mm; narrowly ovoid, winged.
(after Reeve & Woods, 1989).

Colours: Flower colour very variable: white to greenish white suffused with pink, purple or blue especially towards base of sepals and petals and on veins; lip purple, purplish brown, yellowish brown, orange, yellow or green, nerves often darker; anther violet, blue, green or yellow.

Habitat: Epiphyte in rainforest, limestone hill forest, forest clearings or on trees on river banks, usually in light shade. Altitude 100 to 1300 m.

Flowering time in the wild: March, April, June, September, November.

Distribution: New Guinea.

Distribution in New Guinea: Papua (Vogelkop Peninsula, Legare River, Idenburg River, Cyclop Mountains); Papua New Guinea (Sandaun, Western Highlands, Southern Highlands, Madang, Morobe and Central provinces).

Map: CYANOMAP.JPG [Dendrobium cyanocentrum Schltr., distribution map, redrawn from T.M. Reeve & P.J.B. Woods, Notes Roy. Bot. Gard. Edinburgh 46 (1989) 285, map 7 (with new record added).]

Notes: Dendrobium cyanocentrum is the type species of the former section Oxyglossum having been described, along with Dendrobium pentapterum, from material collected by Schlechter during his first expedition to New Guinea in 1901-1902. The sharply pointed reflexed sepals and petals serve to distinguish Dendrobium cyanocentrum from all other species in the section. The flowers are scented like citronellal.
(largely after Reeve & Woods, 1989).

Cultivation: Occurring at rather low altitudes this attractive species is reasonably easy to cultivate under warm-intermediate conditions. It strongly dislikes soggy conditions and therefore requires excellent drainage yet should never be allowed to dry out for long.