Orchids of New Guinea

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Dendrobium johnsoniae

Dendrobium johnsoniae F.Muell., S. Sci. Rec. 2 (1882) 95.

Type: Chalmers s.n. (New Guinea, E. Peninsula) (holo MEL; iso K).

Synonyms:

Sayeria johnsoniae (F.Muell.) Rauschert, Feddes Repert. 94 (1983) 467.
Dendrobium macfarlanei Rchb.f., Gard. Chron. (1882, II) 520 (non F.Muell.).
- Type: Veitch cult. (Macfarlane) s.n. (holo W).
Callista macfarlanei (Rchb.f.) Kuntze, Rev. Gen. Pl. (1891) 655.
Dendrobium monodon Kraenzl., in Engl., Pflanzenr. IV. 50. II. B. 21 (1910) 254.
- Type: Weinland 314 (holo HBG).
Dendrobium niveum Rolfe, Gard. Chron. (1891, I) 104 (nom. nov.).

An erect epiphytic herb. Pseudobulbs stout, subclavate, 4-6-noded below leaves, 20-30 by 0.8-1.1 cm, yellow, 4-5-leaved at apex. Leaves coriaceous, elliptic or oblong-elliptic, obtuse, 8-11 by 3.5-4.5 cm. Inflorescence terminal or from below leaf bases, erect or suberect, 17-27 cm long, few-many-flowered; bracts elliptic-lanceolate, acute, 4-7 mm long. Flowers large, attractive, white with purple lines on side lobes of lip and base of column; pedicel and ovary 1.7-2.2 cm long. Dorsal sepal lanceolate, acuminate, 2.6-2.8 by 0.7-0.8 cm; lateral sepals obliquely lanceolate, acuminate, 2.6-3.4 by 1-1.1 cm; mentum obliquely conical, 8-9 mm long, somewhat nose-like towards apex. Petals narrowly clawed, rhombic above, acuminate, 4.2-5 by 1.8-3 cm. Lip not recurved, 3-lobed, 3.5-4.6 by 2-3 cm; side-lobes erect, subquadrate, with erose margins; midlobe much longer than side-lobes, ovate-lanceolate, acuminate, narrow at base; callus fleshy, obscurely 2-ridged at base. Column short, 3 mm long, with two hook-like stelidia at apex; foot 7-9 mm long.
(after Cribb, 1983).

Colours:

Flowers white with purple to reddish lines on side lobes of lip and base of column.

Habitat:

Epiphyte in montane forests of Araucaria, Albizia, Casuarina etc. Altitude 500 to 1200 m.

Distribution:

New Guinea, Solomon islands.

Distribution New Guinea:

Papua (Manokwari, Yapen Waropen, and Jayapura Regencies); Papua New Guinea (Sandaun, Madang, Morobe, Central, and Oro Provinces).

Map: Dendrobium johnsoniae F.Muell., distribution map, redrawn from P. Cribb, Kew Bull. 38 (1983) 234, map 2, with new records added.

Cultivation:

Intermediate growing epiphyte.

Flowering time in the wild:

April to November.

Classification:

Family Orchidaceae
Subfamily Epidendroideae
Tribe Dendrobieae
Subtribe Dendrobiinae
Genus Dendrobium
Section Latouria
Species Dendrobium johnsoniae

Literature:

Cribb, P.J. 1983. Kew Bull. 38: 260, fig. 7, pl. 12A, C-D, map 2.
Hunt, P.F. 1969. Curtis's Bot. Mag. 177: t. 560 (hybrid!).
Lewis, B. & P.J. Cribb. 1991. Orchids of the Solomon Islands and Bougainville: 175, pl. 9F.
O'Byrne, P. 1994. Lowland Orchids of Papua New Guinea: 276, fig., pl.
Schlechter, R. 1912. Repert. Spec. Nov. Regni Veg. Beih. 1: 492.
Schlechter, R. 1923. Repert. Spec. Nov. Regni Veg. Beih. 21: t. 166, fig. 622.
van Bodegom, J. 1973. Enige orchideeën van West Nieuw Guinea: 72.

Notes:

Dendrobium johnsoniae F.Muell. is similar to Dendrobium rhodostictum F.Muell. & Kraenzl. and Dendrobium otaguroanum A.D.Hawkes but is readily distinguished by its pure white flowers veined with purple-red on the lip side-lobes only, its rhombic petals and an elongate lip with a lanceolate midlobe.

The distribution of Dendrobium johnsoniae F.Muell. in New Guinea and the Solomon Islands closely parallels that of Dendrobium spectabile Blume.
(after Cribb, 1983).