Orchids of New Guinea

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Dendrobium obtusum

Dendrobium obtusum Schltr., in K.Schum. & Lauterb., Nachtr. Fl. Deutsch. Schutzgeb. Südsee (1905) 177.

Type: Schlechter 14451 (holo B, lost).

Synonyms:

Dendrobium concavissimum J.J.Sm., Bull. Jard. Bot. Buitenzorg, sér. 2, 2 (1911) 11; Nova Guinea 12, 1 (1913) 57, t. 16, fig. 45.
- Type: Kock, de 203.
Pedilonum concavissimum (J.J.Sm.) Rauschert, Feddes Repert. 94 (1983) 458.
Dendrobium chrysoglossum Schltr., Repert. Spec. Nov. Regni Veg. Beih. 1 (1912) 509; 21 (1923) t. 173, fig. 645.
- Type: Schlechter 19172 (holo B, lost).
Pedilonum chrysoglossum (Schltr.) Rauschert, Feddes Repert. 94 (1983) 458.
Dendrobium fornicatum Schltr., Repert. Spec. Nov. Regni Veg. Beih. 1 (1912) 509; 21 (1923) t. 173, fig. 644.
- Type: Schlechter 19539 (holo B, lost; iso AMES, BM, BO, G, K, L, NSW, S).
Pedilonum fornicatum (Schltr.) Rauschert, Feddes Repert. 94 (1983) 459.
Dendrobium rhodobotrys Ridl., Trans. Linn. Soc. London, Bot. 9 (1916) 170.
- Type: Kloss s.n. (Camp 6b, 3900 ft); Camp 6c, 5500 ft); (Camp 8 to 9, up to 4900.
Pedilonum rhodobotrys (Ridl.) Rauschert, Feddes Repert. 94 (1983) 463.
Dendrobium lauterbachianum A.D.Hawkes, Orquidea (Mexico City) 28 (1966) 202 (nom. nov., superfl.).
Pedilonum obtusum (Schltr.) Rauschert, Feddes Repert. 94 (1983) 462.
Coelandria chrysoglossa (Schltr.) M.A.Clem., Telopea 10, 1 (2003) 298
Coelandria concavissima (J.J.Sm.) M.A.Clem., Telopea 10, 1 (2003) 298
Coelandria fornicata (Schltr.) M.A.Clem., Telopea 10, 1 (2003) 298
Coelandria obtusa (Schltr.) M.A.Clem., Telopea 10, 1 (2003) 298

Rhizome very short, roots elongated, filiform, flexuose, glabrous. Stems crowded, erect to pendulous, slender, terete, soon becoming grooved, up to 100 by 0.5 cm, with many leaves; often sparsely branched. Leaf sheaths entirely covering the stem. Leaves erect-patent, ligulate to lanceolate-oblong, 2.5-8 by 0.6-1.7 cm, apex apiculate or unequally bilobulate, the lobules obtuse, (sub)coriaceous, soon falling off. Inflorescences lateral from the stems, racemose, short, densely 6-20-flowered. Floral bracts elliptic to ovate, shorter than the pedicel and ovary, apex apiculate to acuminate. Pedicel and ovary 0.8 cm long, clavate, glabrous. Flowers resupinated or not, c. 1.5 cm long. Dorsal sepal elliptic to ovate, 0.6-0.85 cm long, apex obtuse. Lateral sepals obliquely ovate, much widened at the base, 0.6-0.85 cm long, apex obtuse; mentum oblongoid, c. 0.7 cm long, obtuse. Petals obliquely obovate-spathulate, 0.6-0.8 cm long, apex obtuse. Lip concave, cuneate-spathulate, 1-1.7 by 0.5-0.7 cm, near basal third slightly constricted and with a semilunate, hyaline, transverse lamella, margins incurved, entire or minutely subserrulate near apex, apex broadly obtuse, almost truncate, hood-like. Column short, clinandrium 3-lobulate, the lateral lobules rounded or unequally bilobulate, the median tooth-like. Anther subquadrate-rounded, in front truncate to retuse and minutely papillose, glabrous elsewhere.
(after Schlechter, 1905).

Colours:

Sepals and petals pale to brilliant rose-red or violet-pink, the lip similar in colour to the sepals or golden yellow to orange.

Habitat:

Epiphyte in lower montane forest. Altitude 750 to 2000 m.

Distribution:

New Guinea, Solomon Islands.

Distribution New Guinea:

Papua (Manokwari, Sorong, Paniai and Jaya Wijaya Regencies); Papua New Guinea (Sandaun, East Sepik, Madang, Morobe, and Enga Provinces).

Map: Dendrobium obtusum Schltr., distribution map.

Cultivation:

Intermediate growing epiphyte, keep in shade.

Flowering time in the wild:

Throughout the year.

Literature:

Schlechter, R. 1912. Repert. Spec. Nov. Regni Veg. Beih. 1: 508.
Reeve, T.M. & J.J. Wood. 1982. Orchadian 7: 113, fig. 1 & 2 (as Dendrobium concavissimum).
Lewis, B. & P.J. Cribb. 1991. Orchids of the Solomon Islands and Bougainville: 194 (as Dendrobium concavissimum).

Notes:

The proper name for this colourful species is Dendrobium obtusum. Reeve & Wood (1982) argued that this name could not be used because Reichenbach f. already listed a 'Dendrobium obtusa Bl.' in an index to one of his works. But this is just a mistake for Dendrocolla obtusa Bl., as is evident by following the page reference given by Reichenbach, where no mention is made of Dendrobium obtusa. This name therefore in no way invalidates Schlechter's Dendrobium obtusum.