Orchids of New Guinea

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Dendrobium arfakense

Dendrobium arfakense J.J.Sm., Repert. Spec. Nov. Regni Veg. 12 (1913) 29; Nova Guinea 12

Type: Gjellerup 1042 (holo BO).

Synonyms:

Cadetia arfakensis (J.J.Sm.) Schltr., Bot. Jahrb. Syst. 58 (1922) 91.

Basionym: Dendrobium arfakense.

Rhizome short. Stems crowded, erect, slender, slightly thickened in upper part, sharply 4-angular to 4-winged, 5-10 cm by 4-6 mm, 1-leaved. Leaves erect, subfalcate, obliquely linear-lanceolate, 10-12 by 1.4 cm, fleshy-coriaceous, base obtuse, apex unequally acutely bidentate. Inflorescences terminal from the leaf axil, several in succession, 1-flowered; spathe linear-triangular, 1.5 cm by 4.7 mm. Pedicel 1.3 cm long; ovary 0.3 cm long, winged-triangular in cross section. Flower resupinated, c. 1.7 cm long. Dorsal sepal reflexed, oblong, 0.9 cm by 3.4 mm, apex obtuse. Lateral sepals obliquely oblong, free part 1 cm by 3.8 mm, apex obtuse; mentum spur-like, subclavate-fusiform, 0.5 cm long, narrowed at apex, truncate. Petals obliquely linear-lanceolate, 0.85 cm by 1.5-1.6 mm, margins in upper part minutely erose, apex acute or narrowly obtuse. Lip clawed, 3-lobed at the base of the blade, 1 by 0.58 cm (excluding the claw), between the lateral lobes with two keels, on the midlobe with three broader, coarsely verrucose keels, of which the median is shorter and indistinct; lateral lobes erect, obliquely orbicular-quadrangular, 0.2 by 0.27 cm; midlobe large, clawed, the claw from a narrow base dilated to the blade, margins crenulate, 0.33 cm long, pubescent at the base, the blade abruptly widened, transversely semiorbicular-reniform, 0.45 by 0.83 cm, fleshy, apex rounded-bilobulate. Column 0.27 cm long, hairy below the stigma, stelidia obliquely triangular, as long as the triangular, obtuse filament.
(after Smith, 1916).

Colours:

Flower creamy to greenish white, the lip in the centre suffused and finely spotted with reddish violet, becoming yellowish at late anthesis.

Habitat:

Epiphyte in montane forest and limestone hill forest. Altitude 600-1900 m.

Distribution:

New Guinea (endemic).

Distribution New Guinea:

Papua (Sorong and Manowkari Regencies).

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

Cultivation:

Intermediate growing epiphyte, requires light shade and ample watering throughout the year.

Flowering time in the wild:

February, April.

Notes:

Dendrobium arfakense J.J.Sm. is easily recognised by the shape of the lip, of which the midlobe is clawed and very much larger than the almost orbicular lateral lobes.