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Dendrobium polysema

Dendrobium polysema

Dendrobium polysema Schltr., in K.Schum. & Lauterb., Nachtr. Fl. Deutsch. Schutzgeb. Südsee (1905) 163; Repert. Spec. Nov. Regni Veg. Beih. 21 (1923) t. 167, fig. 628.

Type: Schlechter 14046 (holo B, lost).

Synonyms:

  • Dendrobium macrophyllum A.Rich. var. stenopterum Rchb.f., Gard. Chron. (1888, I) 393.
    - Type: Bull cult. s.n. (holo W).
  • Dendrobium stenopterum (Rchb.f.) Chadim, Orchadian 4: 28(1972).
  • Dendrobium pulchrum Schltr., Repert. Spec. Nov. Regni Veg. Beih. 1 (1912) 496; 21 (1923) t. 169, fig. 629.
    - Type: Schlechter 19605 (holo B, lost).
  • Dendrobium polysema Schltr. var. pallidum Chadim, Austral. Orchid Rev. 29 (1964) 32.
    - Type: Chadim D7 (holo K).
  • Sayeria polysema (Schltr.) Rauschert, Feddes Repert. 94 (1983) 468.

An epiphytic herb. Pseudobulbs clavate, 20-50 by 1.5-3 cm, drying yellow or orange, 3-5-noded below leaves, 2-leaved at apex. Leaves spreading, coriaceous, elliptic or oblong-elliptic, obtuse, up to 22 by 6-13 cm, shortly petiolate. Inflorescences terminal, erect to arcuate, few- to many-flowered, up to 45 cm long; peduncle terete, with 3 well-spaced sheaths along length; bracts lanceolate, acute, 1.5-2.5 by 0.6 cm. Flowers medium-sized to large, setose on outer surface; pedicel and ovary 3.6-5 cm long, densely setose. Dorsal sepal ovate-lanceolate, acuminate, 2-2.4 by 1.2-1.4 cm; lateral sepals obliquely falcate-lanceolate, acuminate, 2.3-3 by 1.5 cm; mentum incurved-conical, 1.2 cm long. Petals often reflexed, oblanceolate or obovate, apiculate, 1.8-2.6 by 0.7-1.6 cm, with ± strongly undulate margins. Lip 3-lobed, recurved, 1.8-2.3 by 2-2.6 cm when flattened; side-lobes smaller than midlobe , erect or incurved, tapering to a rounded apex; midlobe flat or with incurved margins, transversely oblong-ovate, subapiculate; callus 3-ridged, with a 4 mm long somewhat dilated free apex. Column short, 3-3.5 mm long, with an upcurved hook on each side at apex; foot incurved, 1.2 cm long.
(after Cribb, 1983).

(after Cribb, 1983).


Sepals yellow or greenish, heavily spotted maroon; petals cream, spotted maroon; lip yellow, spotted maroon on midlobe and striped maroon on side-lobes; callus creamy white.

Epiphyte on tree trunks and thick branches in montane forest. Altitude 1200 to 1900 m.

New Guinea, Solomon Islands, Vanuatu.

Papua New Guinea, widespread, but apparently not west of the Bismarck range.

Map: Dendrobium polysema Schltr., distribution map, redrawn from P. Cribb, Kew Bull. 38 (1983) 234, map 2.

Intermediate growing epiphyte.

January, May, June, August.

  • Schlechter, R. 1912. Repert. Spec. Nov. Regni Veg. Beih. 1: 496.
  • Cribb, P.J. 1980. Curtis's Bot. Mag., n.s. (1980) t. 798.
  • Cribb, P.J. 1983. Kew Bull. 38: 249, fig. 1A-C, pl. 11E.
  • Lewis, B. & P.J. Cribb. 1991. Orchids of the Solomon Islands and Bougainville: 178, fig. 41, pl. 10D.
  • Clements, M. A. and Spence, P. 2017. Re-interpretation of the Dendrobium polysema Schltr. complex (Orchidaceae: Dendrobieae). Australian Journal of Botany 82(2): 2–23.

Dendrobium polysema is closely allied to the widespread Dendrobium macrophyllum A.Rich. but is readily distinguished by its two-leaved pseudobulbs, broader elliptic leaves and the tapering side-lobes and the heavily spotted midlobe of its lip. Its flowers often open widely with the petals often reflexed and the midlobe deflexed giving the flower a flat appearance. Flower size is variable, the larger forms correspond to Dendrobium pulchrum.


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Dendrobium polysema

overview

Dendrobium polysema

Dendrobium polysema Schltr., habit, photo , based on Edinburgh cult. C.5235

Dendrobium polysema

Dendrobium polysema Schltr., inflorescence, photo D. Titmuss, based on P. Spence cult., ex Agaun, PNG

Dendrobium polysema

Dendrobium polysema Schltr., flowers, photo D. Titmuss, based on P. Spence cult., ex Agaun, PNG

Dendrobium polysema

Dendrobium polysema Schltr., flowers, photo J. Meijvogel, based on Leiden cult. 940418

Dendrobium polysema

Dendrobium polysema Schltr., flower, photo J. Meijvogel, based on Leiden cult. 940418

Dendrobium polysema

Dendrobium polysema Schltr., flower detail, photo P. Jongejan, based on Jongejan 1539

Dendrobium polysema

Dendrobium polysema Schltr., flower detail, photo P. Jongejan, based on Jongejan 1539

Dendrobium polysema

Dendrobium polysema Schltr., flower, photo D. Titmuss, based on P. Spence cult, ex Agaun, PNG

Dendrobium polysema

Dendrobium polysema Schltr., photo John Cara, plant habit, cult., from PNG.

Dendrobium polysema

Dendrobium polysema Schltr., photo John Cara, flower, front view, cult., from PNG.

Dendrobium polysema

Dendrobium polysema Schltr., photo John Cara, flower, front view, cult., from PNG.

Dendrobium polysema

Dendrobium polysema Schltr., photo John Cara, flower, front view, cult., from PNG.

Dendrobium polysema

Dendrobium polysema Schltr., photo John Cara, flower, oblique lateral view, cult., from PNG.

Dendrobium polysema

Dendrobium polysema Schltr., photo John Cara, flower, lateral view, cult., from PNG.

Dendrobium polysema

Dendrobium polysema Schltr., photo John Cara, flower, front view, cult.John Cara, from PNG.

Dendrobium polysema

Dendrobium polysema Schltr., photo John Cara, flower detail, centre of flower, front view, cult.John Cara, from PNG.

Dendrobium polysema

Dendrobium polysema Schltr. ("D. pulchrum"), photo John Cara, flower detail, centre of flower, various colour forms front view, cult.John Cara, from PNG.s

Dendrobium polysema

Dendrobium polysema Schltr., pale forms, photos John Cara, flower, front view, cult., from PNG.

Dendrobium polysema

Dendrobium polysema Schltr. ("D. stenopterum"), photo John Cara, plant habit, cult. John Cara, from PNG, Kar Kar island

Dendrobium polysema

Dendrobium polysema Schltr. ("D. stenopterum"), photo John Cara, flowers, various vieuws, cult. John Cara, from PNG, KakKar island

Dendrobium polysema

Dendrobium polysema Schltr. ("D. stenopterum"), photo John Cara, flower detail, centre of flower, cult. John Cara, from PNG

Dendrobium polysema

Dendrobium polysema Schltr., infloreescence, photo Ed de Vogel, Stocker cult. s.n., from Papua New Guinea, without locality

Dendrobium polysema

Dendrobium polysema Schltr., flower, front view, photo Ed de Vogel, Stocker cult. s.n., from Papua New Guinea, without locality

Dendrobium polysema

Dendrobium polysema Schltr., flower, oblique lateral view, photo Ed de Vogel, Stocker cult. s.n., from Papua New Guinea, without locality

Dendrobium polysema

Dendrobium polysema Schltr., flower, front view, photo Ed de Vogel, Stocker cult. s.n., from Papua New Guinea, without locality

Dendrobium polysema

Dendrobium polysema Schltr., flower, oblique lateral view, photo Ed de Vogel, Stocker cult. s.n., from Papua New Guinea, without locality

Dendrobium polysema

Dendrobium polysema Schltr., inflorescence, photo Ed de Vogel, Stocker cult. s.n., from Papua New Guinea, without locality

Dendrobium polysema

Dendrobium polysema Schltr., flower, front view, photo Ed de Vogel, Stocker cult. s.n., from Papua New Guinea, without locality

Dendrobium polysema

Dendrobium polysema Schltr., flower, front view, photo Ed de Vogel, Stocker cult. s.n., from Papua New Guinea, without locality

Dendrobium polysema

Dendrobium polysema Schltr., flower, oblique front view, photo Ed de Vogel, Stocker cult. s.n., from Papua New Guinea, without locality

Dendrobium polysema

Dendrobium polysema Schltr., drawing John Cara, flower analyses, from PNG, Milne Bay Prov.

Dendrobium polysema

Dendrobium polysema Schltr., colour pencil drawing John Cara, flower analyses, from PNG, Milne Bay Prov., Agaun

Dendrobium polysema

Dendrobium polysema Schltr., drawing John Cara, plant habit and flower analyses, fom PNG, Milne Bay.

Dendrobium polysema

Dendrobium polysema Schltr., drawing John Cara, plant habit and flower analyses, from PNG.

Dendrobium polysema

Dendrobium polysema Schltr. var. pallidum Chadim, ., drawing John Cara, flower analysos, from PNG.Auguan

Dendrobium polysema

Dendrobium polysema Schltr. var. pallidum Chadim, ., drawing John Cara, flower analyses, from PNG.

Dendrobium polysema

Dendrobium polysema Schltr., drawing by S.P. Hillier in Kew Bull. 38 (1983) 244, fig. 1 A-C

Dendrobium polysema

Dendrobium polysema Schltr., drawing R. Schlechter in Repert. Spec. Nov. Regni Veg. Beih. 21 (1923) t. 167, fig. 628

Dendrobium polysema

Dendrobium polysema Schltr. (as Dendrobium pulchrum Schltr.), drawing R. Schlechter in Repert. Spec. Nov. Regni Veg. Beih. 21 (1923) t. 169, fig. 629