Dendrobium otaguroanum

Dendrobium otaguroanum A.D.Hawkes, Lloydia 20 (1957) 122 (nom. nov.).

Basionym: Dendrobium chloroleucum Schltr.

A small epiphytic herb. Pseudobulbs clustered, erect, 10-25 by 0.3-0.7 cm, 3-4-noded below leaves, yellow, 2-3-leaved at apex. Leaves coriaceous, narrowly lanceolate to ovate, acute, 5-7 by 1.2-2.1 cm. Inflorescence erect, 2.5-6.7 cm long, 2-6(or more)-flowered; bracts elliptic, apiculate, 4 mm long. Flowers subnutant; pedicel and ovary 1.7-2.5 cm long; ovary somewhat rugulose. Dorsal sepal ovate-lanceolate, acuminate, 1.6-1.8 by 0.5 cm; lateral sepals obliquely lanceolate, acuminate, 1.6-2 by 0.8-1 cm broad; mentum obliquely conical, 7-8 mm long. Petals obovate, obtuse or apiculate, 1.6-1.5 by 0.8-1 cm. Lip entire, obovate, apiculate, narrowly clawed at base, 1.6-2.2 by 1.5-1.6 cm; callus fleshy, 3-ridged, over half length of lip. Column 2.5 mm long; foot 7-8 mm long.
(after Cribb, 1983).

Colours: Flowers white with yellowish green venation on the lip.

Habitat: Epiphyte in montane forests of Nothofagus, Podocarpus, Castanopsis, etc. Altitude 1500 to 2200 m.

Flowering time in the wild: January, March, October.

Distribution: New Guinea.

Distribution in New Guinea: Papua (widespread); Papua New Guinea .

Map: OTAGUMAP.JPG [Dendrobium otaguroanum A.D.Hawkes, distribution map, redrawn from P. Cribb, Kew Bull. 38 (1983) 242, map 3.]

Notes: Dendrobium otaguroanum is most closely allied to Dendrobium rhodostictum but differs in having smaller flowers with an entire obovate lip lacking any rose-purple spotting on its margin. In flower size it is much closer to the Pacific Islands species Dendrobium ruginosum and Dendrobium mooreanum but they are both readily distinguished by their angulate pseudobulbs and narrower lips, somewhat oblong to rhombic in outline.
Dendrobium otaguroanum is apparently restricted in its distribution to mainland New Guinea but recently a collection was sent to Kew by G. H. Slade from Panguna in Bougainville which closely resembled this species in its flower structure. Large populations of Dendrobium rhodostictum and Dendrobium ruginosum grow on steep man-made slopes by the road at Panguna and field studies did confirmed Cribb's (1983) suspicion that the Slade collection is not Dendrobium otaguroanum but rather a primary hybrid of Dendrobium rhodostictum and Dendrobium ruginosum.

Cultivation:Cool growing epiphyte.