Orchids of New Guinea

Dendrobium transversilobum

Dendrobium transversilobum J.J.Sm., Bull. Dép. Agric. Indes Néerl. 39 (1910) 11; Nova Guinea 8

Type: Bogor cult. (Branderhorst 203) (syn BO, K); Römer, von 661(syn BO).

Synonyms:

Cadetia transversiloba (J.J.Sm.) Schltr., Repert. Spec. Nov. Regni Veg. Beih. 1 (1912) 424.
Cadetia heterochroma Schltr., Repert. Spec. Nov. Regni Veg. Beih. 1 (1912) 437; 21 (1923) t. 151, fig. 567.
- Type: Schlechter 20014 (holo B, lost; iso L).
Dendrobium heterochromum (Schltr.) J.J.Sm., Bull. Jard. Bot. Buitenzorg, sér. 2, 8 (1912) 18.

Rhizome very short. Stems crowded, erect, clavate, sharply 4-winged, 5-7 cm by 5-7 mm, 1-leaved. Leaves erect, oblong to elliptic-oblong, 9-10 by 3.3-4 cm, fleshy, base broadly obtuse, margins recurved, apex shortly bilobulate. Inflorescences terminal from the leaf axil, fascicled, arising in succession, 1-flowered; spathe 1.3-1.5 cm long. Pedicel and ovary 0.7 cm long, angled, with two sharp undulating wings. Flower c. 1 cm across. Dorsal sepal broadly ovate, 0.45 cm by 4 mm, apex acute. Lateral sepals obliquely ovate, 0.5 cm by 4.5 mm, apex subacute; mentum spur-like, subcylindrical, the apical part almost rectangularly recurved, the basal part 0.35 cm, the apical part 0.4 cm long, apex obtuse, emarginate. Petals obliquely ovate, 0.4 cm by 3.3 mm, apex short acuminate, the very tip narrowly obtuse. Lip clawed, 3-lobed at the base of the blade, blade 0.46 cm long, in natural position 0.38 cm, when flattened 0.55 cm wide, on the disk with a pubescent swelling which terminates in an obtuse horizontal tooth at the base of the midlobe; lateral lobes erect, obliquely quadrangular, rather fleshy, truncate; midlobe recurved, ovate-orbicular, when flattened almost semiorbicular, 0.3 by 0.37 cm, fleshy, minutely pubescent at the base, apex obtuse. Column 0.25 cm long, margins pubescent, stelidia conical, obtuse, stigma transversely quadrangular; column-foot pubescent inside. Anther transversely cucullate, 1.6 mm wide.
(after Smith, 1909).

Colours:

Sepals pale greenish yellow, tips often suffused with dull purple, petals coloured as the sepals, but usually tinged darker (red-) purple. Lip whitish, the lateral lobes inside minutely spotted purple, at the apex with or without a small purple spot.

Habitat:

Epiphyte in lowland rainforest and hill forest, also on limestone, often growing on the trunks of very small trees in fairly shaded positions. Altitude 0-600 m.

Distribution:

New Guinea (endemic).

Distribution New Guinea:

Papua (Sorong, Nabire, Merauke, Timika Mimika, and Jayapura Regencies); Papua New Guinea (Sandaun, Western, Central and Oro Provinces).

Map: Dendrobium transversilobum J.J.Sm., distribution map.

Cultivation:

Warm growing epiphyte, keep in shade.

Flowering time in the wild:

Throughout the year.

Literature:

Smith, J.J. 1916. Nova Guinea 12, 3: 284.
O'Byrne, P. 1994. Lowland Orchids of Papua New Guinea: 164, fig., pl.

Notes:

Dendrobium transversilobum J.J.Sm. is a locally common and easily recognised lowland species. The almost hammer-shaped mentum, the colours, and the broad elliptic-oblong leaves are all distinctive.