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Dendrobium rhodostictum

Dendrobium rhodostictum

Dendrobium rhodostictum F.Muell. & Kraenzl., Ă–sterr. Bot. Zeitschr. 44 (1894) 300.

Type: Sayer s.n. (1887, Bourawarri (camp 9), New Guinea) (holo HBG).

Synonyms:

  • Dendrobium madonnae Rolfe ex Hook.f., Bot. Mag. 129 (1903) t. 7900.
    - Type: Sander cult. s.n. (1899, New Guinea) (holo K).
  • Sayeria rhodosticta (F.Muell. & Kraenzl.) Rauschert, Feddes Repert. 94 (1983) 468.

Epiphytes or sometimes terrestrials, herbaceous, erect. Pseudobulbs tufted, narrowly fusiform (New Britain), or thin reedlike with only the 3-5-upper internodes abrubtly and markedly dilated into an ovoid pseudobulb (Bougainville), 9-25 by 0.3-1.2 cm, 2-4-leaved at apex. Leaves suberect or spreading, coriaceous, ovate-lanceolate to linear-lanceolate, minutely emarginate at acute to obtuse apex, 5-11 by 1-2.5 cm. Inflorescences apical or subapical, erect to arcuate, few-flowered; bracts elliptic, acute, 3-4 mm long. Flowers subnutant, white with purple spots on side margins of lip; pedicel and ovary 2.5-3.5 cm. Dorsal sepal ovate, acute or acuminate, 1.8-2.5 by 1 cm; lateral sepals falcate-lanceolate, acuminate, 1.8-2.2 by 1-1.1 cm; mentum obliquely conical, 8-10 mm long. Petals obovate-spathulate, obtuse to apiculate, 3-3.5 by 1.5-2.4 cm. Lip obscurely 3-lobed towards apex, broadly obovate in outline 1.9-2.6 by 1.8-2.8 cm; side-lobes erect-incurved, semicircular, often overlapping and larger than midlobe ; midlobe often obscure, transversely oblong to ovate, apiculate; callus 3-ridged above, raised and 3-lobed at base. Column 2.5 mm long; foot 7-9 mm long.
(after Cribb, 1983).



Paeudobulbs dull yellowish. Flowers white with purple spots on side margins of lip.

Epiphyte in montane forest on Castanopsis, Nothofagus, etc. or terrestrial on steep wet mossy slopes; 800-1200 m.

New Guinea, Bismarck Archipelago, Solomon Islands.

Papua New Guinea (Karkar Island; Milne Bay Province; New Britain; New Ireland).

Map: Dendrobium rhodostictum F.Muell. & Kraenzl., distribution map, redrawn from P. Cribb, Kew Bull. 38 (1983) 250, map 4.

Intermediate growing epiphyte.

January, May, June.

  • Schlechter, R. 1912. Repert. Spec. Nov. Regni Veg. Beih. 1: 491.
  • Schlechter, R. 1923. Repert. Spec. Nov. Regni Veg. Beih. 21: t. 167, fig. 621.
  • Cribb, P.J. 1983. Kew Bull. 38: 268, fig. 8E, F, 10, pl. 13A, B, map 4.
  • Lewis, B. & P.J. Cribb. 1991. Orchids of the Solomon Islands and Bougainville: 179, pl 10B.

Characteristic for Dendrobium rhodostictum is the broad lip, which is three-lobed, apiculate, difficult to flatten and has rose-purple spots outside on the lateral margins and similar coloured stripes on the inside of the lip, which both shimmer through on the other side.

Specimens from New Britain have somewhat larger flowers with a more markedly three-lobed lip than those from New Guinea or Bougainville, and in addition also have pseudobulbs which are somewhat swollen along their entire length, instead of abruptly dilated in the apical part. ontrary to Cribb's (1983) opinion, we think that the vegetative and floral differences may warrant taxonomic recognition at subspecies level.


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Dendrobium rhodostictum

Dendrobium rhodostictum F.Muell. & Kraenzl., flower, front view, photo Ed de Vogel, based on Leiden cult. 20081750.

Dendrobium rhodostictum

Dendrobium rhodostictum F.Muell. & Kraenzl., photo John Cara, plant habit, cult. John Cara, from PNG.

Dendrobium rhodostictum

Dendrobium rhodostictum F.Muell. & Kraenzl., photo John Cara, inflorescence, cult. John Cara, from PNG.

Dendrobium rhodostictum

Dendrobium rhodostictum F.Muell. & Kraenzl., photo John Cara, inflorescence, cult. John Cara, from PNG.

Dendrobium rhodostictum

Dendrobium rhodostictum F.Muell. & Kraenzl., photo John Cara, flower, front view, cult. John Cara, from PNG.

Dendrobium rhodostictum

Dendrobium rhodostictum F.Muell. & Kraenzl., photo John Cara, inflorescence, cult. John Cara, from PNG.

Dendrobium rhodostictum

Dendrobium rhodostictum F.Muell. & Kraenzl., photo John Cara, flower, front view, cult. John Cara, from PNG.

Dendrobium rhodostictum

Dendrobium rhodostictum F.Muell. & Kraenzl., photo John Cara, flower, oblique front view, cult. John Cara, from PNG.

Dendrobium rhodostictum

overview

Dendrobium rhodostictum

Dendrobium rhodostictum F.Muell. & Kraenzl., habit, photo A. Schuiteman, based on Leiden cult. 940328

Dendrobium rhodostictum

Dendrobium rhodostictum F.Muell. & Kraenzl., inflorescence, photo J. Meijvogel, based on Leiden cult. 940328

Dendrobium rhodostictum

Dendrobium rhodostictum F.Muell. & Kraenzl., inflorescence, photo A. Schuiteman, based on Leiden cult. 940328 (Jongejan), from Papua New Guineea, Bougainville

Dendrobium rhodostictum

Dendrobium rhodostictum F.Muell. & Kraenzl., flower, photo A. Schuiteman, based on Leiden cult. 940328 (Jongejan), from Papua New Guineea, Bougainville

Dendrobium rhodostictum

Dendrobium rhodostictum F.Muell. & Kraenzl., lip, photo A. Schuiteman, based on Leiden cult. 940328 (Jongejan), from Papua New Guineea, Bougainville

Dendrobium rhodostictum

Dendrobium rhodostictum F.Muell. & Kraenzl., habit, photo A. Schuiteman, based on Leiden cult. 940328 (Jongejan), from Papua New Guinea, Bougainville

Dendrobium rhodostictum

Dendrobium rhodostictum F.Muell. & Kraenzl., flower, oblique lateral view, photo Ed de Vogel, Leiden cult. 20081750 (de Vogel & Raka), from Papua New Guinea, East New Guinea Province

Dendrobium rhodostictum

Dendrobium rhodostictum F.Muell. & Kraenzl., flower, front view, photo Ed de Vogel, based on Leiden cult. 20081750 (de Vogel & Raka), from Papua New Guinea, East New Guinea Province

Dendrobium rhodostictum

Dendrobium rhodostictum F.Muell. & Kraenzl., flower, frontl view, photo Ed de Vogel, Leiden cult. 20081750 (de Vogel & Raka), from Papua New Guinea, East New Guinea Province

Dendrobium rhodostictum

Dendrobium rhodostictum F.Muell. & Kraenzl., flower, oblique front view, photo Ed de Vogel, Leiden cult. 20081750 (de Vogel & Raka), from Papua New Guinea, East New Guinea Province

Dendrobium rhodostictum

Dendrobium rhodostictum F.Muell. & Kraenzl., flower, oblique lateral view, photo Ed de Vogel, Leiden cult. 20081750 (de Vogel & Raka), from Papua New Guinea, East New Guinea Province

Dendrobium rhodostictum

Dendrobium rhodostictum F.Muell. & Kraenzl., flower, lateral view, photo Ed de Vogel, Leiden cult. 20081750 (de Vogel & Raka), from Papua New Guinea, East New Guinea Province

Dendrobium rhodostictum

Dendrobium rhodostictum F.Muell. & Kraenzl. (as Dendrobium madonnae Rolfe ex Hook.f.), habit, colour plate from Curtis's Bot. Mag. 129 (1903) t. 7900

Dendrobium rhodostictum

Dendrobium rhodostictum F.Muell. & Kraenzl., drawing by N.H.S. Howcroft in Kew Bull. 38 (1983) 269, fig. 10

Dendrobium rhodostictum

Dendrobium rhodostictum F.Muell. & Kraenzl., drawing by Neville Howcroft, based on W. Takeuchi & J. Waikabu 9514 in Sida 20 (2002) 482, fig. 16.

Dendrobium rhodostictum

Dendrobium rhodostictum F.Muell. & Kraenzl., drawing John Cara, plant habit and flower analyses, fom PNG.

Dendrobium rhodostictum

Dendrobium rhodostictum F.Muell. & Kraenzl., drawing R. Schlechter in Repert. Spec. Nov. Regni Veg. Beih. 21 (1923) t. 167, fig. 621

Dendrobium rhodostictum

Dendrobium rhodostictum F.Muell. & Kraenzl. (as Dendrobium madonnae Rolfe ex Hook.f.), floral details, drawing from Curtis's Bot. Mag. 129 (1903) t. 7900

Dendrobium rhodostictum

Dendrobium rhodostictum F.Muell. & Kraenzl., drawing by S.P. Hillier in Kew Bull. 38 (1983) 263, fig. 8 E, F