Orchids of New Guinea

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Dendrobium trilamellatum

Dendrobium trilamellatum J.J.Sm., Bull. Dép. Agric. Indes Néerl. 19 (1908) 21; Nova Guinea 8, 1 (1909) 69, t. 24, fig. 76.

Type: Bogor cult. (Jaheri 1901, Merauke) s.n.; Bogor cult. (den Berger 1906, Gulf Macclure) s.n. (syntypes BO).

Synonyms:

Cepobaculum trilamellatum (J.J.Sm.) M.A.Clem. & D.L.Jones, Orchadian 13 (2002) 486
Dendrobium johannis Rchb.f. var. semifuscum Rchb.f., Gard. Chron. 1883 (1883) 368.
- Type: Australia, Queensland, cult. W. Bull (holo W).
Dendrobium semifuscum (Rchb.f.) Lavarack & P.J.Cribb, Orchadian 6 (1980) 209.
Cepobaculum semifuscum (Rchb.f.) M.A.Clem. & D.L.Jones, Orchadian 13 (2002) 486

An epiphytic herb. Stems 30-50 cm long, 1.3-1.4 cm diam., narrowly fusiform, somewhat cane-like, nodes 3-5 cm apart, leaves clustered in the apical quarter of stem. Leaves fleshy-coriaceous, linear-lanceolate, acutely bidentate or obliquely acute at apex, up to 14 by 1.65 cm, articulated to sheathing bases. Inflorescences suberect to spreading, laxly few- to many-flowered, up to 50 cm long; peduncle shorter than rachis, up to 16 cm long; bracts minute, triangular, 2 mm long. Flowers fragrant; pedicel and ovary 2-3 cm long. Dorsal sepal erect, linear-lanceolate, acute, 2-3 by 0.4-0.6 cm, spirally twisted; lateral sepals recurved, obliquely linear-lanceolate, acute, 2.7-3.2 by 0.9-1 cm, twisted; mentum obliquely conical, at right angles to the ovary, 8-10 mm long. Petals suberect, linear, acute, 2.2-3 by 0.3 cm, two- or three-times twisted. Lip porrect, 3-lobed, 1.6-2 by 0.7-1 cm; side-lobes oblong-elliptic, obtuse; midlobe convex, ovate to circular, obtuse, as wide as lip across side lobes, 0.7-1 by 0.7-1 cm; callus of 3 ridges to apex of midlobe, dilated somewhat and broken towards apex. Column 5-7 mm long, denticulate at apex; anther cap apically notched.
(after Cribb, 1986).

Colours:

Leaf sheath pale green striped with red. Sepals and petals yellow to yellow-brown; lip yellow lined with purple.

Habitat:

Epiphyte in savannah, often seasonally swampy (fide O'Byrne).

Distribution:

Australia (Queensland), New Guinea.

Distribution New Guinea:

Papua (Manokwari and Merauke Regencies); Papua New Guinea (Western Province).

Map: Dendrobium trilamellatum J.J.Sm., distribution map, redrawn from P. Cribb, Kew Bull. 41 (1986) 644, map 4, with new records added.

Cultivation:

Warm growing epiphyte, sensitive to excess watering.

Flowering time in the wild:

June-July.

Classification:

Family Orchidaceae
Subfamily Epidendroideae
Tribe Dendrobieae
Subtribe Dendrobiinae
Genus Dendrobium
Section Spatulata
Species Dendrobium trilamellatum

Literature:

Cribb, P.J. 1986. Kew Bull. 41: 644, pl. 8D, E, map 4.
O'Byrne, P. 1994. Lowland Orchids of Papua New Guinea: 240, fig., pl.
Smith, J.J. 1935. Orchid Rev. 43: 152.
van Bodegom, J. 1973. Enige orchideeën van West Nieuw Guinea: 102.

Notes:

Dendrobium trilamellatum is closely allied to and often confused with the sympatric Dendrobium johannis. It differs, however, in being a larger plant with usually larger flowers, distinctively coloured yellow, yellow-brown or ochre petals, a mentum at a right angle to the ovary, and a lip in which the midlobe is as broad as the width of the lip across the lateral lobes.
(after Cribb, 1986).