Orchids of New Guinea

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Dendrobium lawesii

Dendrobium lawesii F.Muell., Melbourne Chem. Druggist (1884).

Type: Lawes s.n. (holo MEL).

Synonyms:

Dendrobium warburgianum Kraenzl., Bot. Jahrb. Syst. 13 (1891) 280.
- Type: Warburg s.n. (Sattelberg) (holo HBG).
Dendrobium pseudomohlianum Kraenzl., in K.Schum. & Lauterb., Nachtr. Fl. Deutsch. Schutzgeb. Südsee (1905) 178.
- Type: Brown, F.H. 182 (holo B, lost).
Dendrobium lawesii F.Muell. var. salmonicolor Schltr., Repert. Spec. Nov. Regni Veg. Beih. 1 (1912) 513.
- Type: Schlechter 19131 (holo B, lost).
Dendrobium delphinioides R.S.Rogers, Trans. & Proc. Roy. Soc. South Australia 49 (1925) 262.
- Type: Lane-Poole 394 (iso BRI).
Pedilonum lawesii (F.Muell.) Rauschert, Feddes Repert. 94 (1983) 461.
Chromatotriccum delphinioides (R.S.Rogers) M.A.Clem. & D.L.Jones, Orchadian 13 (2002) 494
Chromatotriccum lawesii (F.Muell.) M.A.Clem. & D.L.Jones, Orchadian 13 (2002) 494

Rhizome short, roots 1-2 mm diameter. Stems crowded, pendulous, slender to rather thick, unbranched, 7-65 cm long, 4-6 mm diameter, leafy throughout their length, internodes 1-2 cm long. Leaf sheaths a little longer than the internodes, glabrous or slightly warty. Leaves (sub)patent, twisted at the base, therefore spreading in one plane with the stem, ovate-lanceolate, 4.5-7 by 1-2 cm, papyraceous, margins near the apex denticulate, apex acuminate. Inflorescences laterally from the defoliated stem, racemose, very short, densely 1-8-flowered. Floral bracts ovate, 2-5 mm long, acute. Pedicel and ovary 2.5-3.5 cm long, ovary microscopically hairy. Flowers 2.5-3.5 cm long. Dorsal sepal broadly ovate-oblong, 0.7-0.8 cm by 3-4 mm, abruptly acute. Lateral sepals free part broadly obliquely ovate-oblong, 7-8 mm wide, apex obtuse; mentum narrowly conical, 2.2-3 cm long, acute, in front closed for about half its length. Petals lanceolate-oblong, 0.7-0.8 cm by 2.5-3.5 mm, acute. Lip spathulate, 2.6-3 cm by 0.8-0.9 cm when flattened, base linear, adnate to the apical half of the column-foot, at about one third above the base with a U-shaped callus, apex inflexed, margin minutely denticulate. Column c. 5 mm long, stelidia short, column-foot 2.2-3 cm long. Pollinia 4, attached to a sticky white substance derived from the rostellum.
(largely after Kraenzlin, 1910, and O'Byrne, 1994).

Colours:

Variable

Habitat:

Epiphyte in lower montane forest. Altitude 650-1500 m.

Distribution:

New Guinea, Louisiades, Solomon Islands.

Distribution New Guinea:

Papua (Sorong Regency); Papua New Guinea (Enga, Southern Highlands, Morobe, Central, Oro and Milne Bay Provinces).

Cultivation:

Intermediate growing epiphyte, requires year-round watering and a light, but not sunny position.

Flowering time in the wild:

Throughout the year.

Literature:

Kraenzlin, F. 1910. Orchidaceae-Monandrae-Dendrobiinae I. In A. Engler, Das Pflanzenreich IV.50.II.B.21: 126.
Schlechter, R. 1912. Repert. Spec. Nov. Regni Veg. Beih. 1: 512.
Schlechter, R. 1923. Repert. Spec. Nov. Regni Veg. Beih. 21: t. 174, fig. 648.
Hunt, P.F. 1968. Curtis's Bot. Mag. 176: t. 524.
Lewis, B. & P.J. Cribb. 1991. Orchids of the Solomon Islands and Bougainville: 158, fig. 35 m-o.
O'Byrne, P. 1994. Lowland Orchids of Papua New Guinea: 296, fig.

Notes:

Dendrobium lawesii is a variable and widespread species, but the several forms illustrated here under the name Dendrobium lawesii may not all represent the 'real' Dendrobium lawesii. The original description by von Mueller is extremely vague and applies to virtually any related species. A revision based on all available material is urgently needed. Undoubtedly more names will be added to the list of synonyms of Dendrobium lawesii. This seems to be the likely fate of Dendrobium macrogenion, Dendrobium conicum, and others.