Orchids of New Guinea

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Dendrobium masarangense

Dendrobium masarangense Schltr., Repert. Spec. Nov. Regni Veg. 10 (1911) 78.

Type: Indonesia, North Sulawesi, Minahassa Peninsula, Mt. Masarang, 1200m, xi 1909, Schlechter 20473 (B, lost). Neotype (designated by T.M.Reeve & P.Woods 1990)

Synonyms:

Dendrobium caespitificum Ridl., Trans. Linn. Soc. London, Bot. 9 (1916) 171 (= subsp. theionanthum var. theionanthum).
- Type: Kloss s.n. (Camp 6c, 5500 ft.) (holo BM).
Pedilonum caespitificum (Ridl.) Rauschert, Feddes Repert. 94 (1983) 458.
Dendrobium chlorinum Ridl., Trans. Linn. Soc. London, Bot. 9 (1916) 172 (= subsp. theionanthum var. chlorinum).
- Type: Kloss s.n. (Camp 6b, 3900 ft.); (Camp 6c, 5500 ft) (syn BM, iso K).
Pedilonum chlorinum (Ridl.) Rauschert, Feddes Repert. 94 (1983) 458.
Dendrobium frigidum Schltr., Repert. Spec. Nov. Regni Veg. Beih. 1 (1912) 534; 21 (1923) t. 181, fig. 676 (= subsp. theionanthum var. theionanthum).
- Type: Schlechter 18723 (holo B, lost, iso NSW).
Pedilonum frigidum (Schltr.) Rauschert, Feddes Repert. 94 (1983) 459.
Dendrobium gemma Schltr., Bot. Jahrb. Syst. 58 (1923) 108 (= subsp. theionanthum var. theionanthum).
- Type: Ledermann 1715 (holo B, lost).
Dendrobium monogrammoides J.J.Sm., Nova Guinea 14 (1929) 431, pl. 68, 80 (= subsp. theionanthum var. theionanthum).
- Type: [ Lam 1438 (holo L, iso BO); para: Lam 1581.
Dendrobium pseudofrigidum J.J.Sm., Nova Guinea 14 (1929) 426, pl. 67, 76 (= subsp. theionanthum var. theionanthum).
- Type: Pulle 886 (holo BO?, iso K, L); para Doorman 10; Lam 1776; 1883; 1950; 1951
Dendrobium pumilio Schltr., Repert. Spec. Nov. Regni Veg. Beih. 1 (1912) 527; 21 (1923) t. 178, fig. 666 (= subsp. masarangense).
- Type: Schlechter 16545 (B, lost; AMES, BO, E, G, K, L, NSW); 17998 (B, lost; iso NSW); 19165 (B, lost); 20267 (B, lost).
Pedilonum pumilio (Schltr.) Rauschert, Feddes Repert. 94 (1983) 462.
Dendrobium theionanthum Schltr., Repert. Spec. Nov. Regni Veg. Beih. 1 (1912) 528; 21 (1923) t. 178, fig. 667 (= subsp. theionanthum var. theionanthum).
- Type: Schlechter 19630 (holo B, lost, iso AMES, BO, E, G, K, L, NSW).
Pedilonum theionanthum (Schltr.) Rauschert, Feddes Repert. 94 (1983) 464.
Oxyglossellum theionanthum (Schltr.) M.A.Clem. & D.L.Jones, Orchadian 13 (2002) 490

Erect tufted epiphyte, 1.5-7 cm high. Roots 0.4-0.8 mm diameter. Rhizome usually very short, rarely elongated and branching. Pseudobulbs 0.2-2(-3) by 0.1-0.35 cm, globose, obclavate, fusiform or cylindrical, apex 2-3(-4)-leaved. Leaves 1-5.5 by 0.05-0.2(-0.35) cm, erect to spreading, linear to lanceolate or subulate-filiform, occasionally semi-terete, rigid, apex acute; sheaths smooth, membranous, with age becoming fibrous. Inflorescences terminal, arising mainly from leafy stems, 1-3-flowered, subsessile or with distinct peduncle to 3 mm long; bracts ovate, apiculate to acuminate. Flowers 0.8-1.7 cm (very rarely to 2.2 cm) long, usually widely opening, occasionally with sepals and petals reflexed, lasting c.6 months. Median sepal 3-7(-9) by 1-2.5 mm, ovate-lanceolate, elliptic (occasionally to obovate), obtuse to acuminate. Lateral sepals 7-15(-18) by 1.5-3(-4) mm, usually markedly oblique, narrowly triangular to ovate, subacute to acuminate or apiculate; basal fused part 2-5(- 7) mm long, cylindrical to subconical, sometimes markedly incurved; mentum total length 4.5- 10(-12) mm, tip obtuse sometimes bilobed. Petals 3-7(-9) by 0.5-1.7 mm, linear, lanceolate or subspathulate, subacute to acuminate. Lip 5.5-14(-17) by 1-2 mm, subtrilobate, linear-oblanceolate, adnate to column foot at base with upper margins incurved, without a cross-ridge, apex narrowly triangular, cuspidate, unbent, slightly deflexed to markedly recurved. Column 1.5-2 mm long; foot 4.5-10(-12) mm long; anther 1-1.5 mm broad; pollinia 0.5-l mm long. Ovary 5-ribbed, often very indistinct with lateral two ribs much reduced (sometimes almost absent), glabrous, shortly papillose or hairy; pedicel and ovary 6-21 mm long. Fruit 8 by 4 mm, ellipsoid.
(after Reeve & Woods, 1989).

Dendrobium masarangense is most closely allied to Dendrobium sulphureum but differs in the generally small size of the plants, the narrower leaves and in the usually smaller flowers which have a 5-ribbed (not triangular) ovary. Occasionally the indistinct ovary cross-sections may cause confusion but the species key takes account of this variation and should lead to the correct identification.
(after Reeve & Woods, 1989).

INFRASPECIFIC TAXA

Key to subspecies and varieties:

1a. Flowers white; mentum often incurved (lowland plant below 1200 m) ... Dendrobium masarangense Schltr. subsp. masarangense
1b. Flowers orange, yellow, greenish-yellow or greenish white; mentum not incurved (highland plant above 1200 m except in Eastern Papua New Guinea) ... 2.

2a. Ovary glabrous or shortly papillate ... Dendrobium masarangense Schltr. subsp. theionanthum (Schltr.) T.M.Reeve & P.Woods var. theionanthum
2b. Ovary hairy ... Dendrobium masarangense Schltr. subsp. theionanthum (Schltr.) T.M.Reeve & P.Woods var. chlorinum (Ridl.) T.M.Reeve & P.Woods.

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Dendrobium masarangense Schltr. subsp. masarangense.

This subspecies has a very wide distribution but is rather poorly represented in herbarium collections. Presumably it is often overlooked in the relatively tall lowland forests, due to its small size, narrow grass-like leaves and pale flowers. Schlechter (1912) recorded it as occurring in 'dense colonies consisting of large numbers of individuals'. In Sulawesi it has only been recorded once.

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Dendrobium masarangense Schltr. subsp. theionanthum (Schltr.) T.M.Reeve & P.Woods, Notes Roy. Bot. Gard. Edinburgh (1989, publ. 1990) 193, var. theionanthum.

Basionym: Dendrobium theionanthum Schltr.

The large variation in plant form noted for this subspecies is due mainly, it seems, to the degree of exposure to the sun. Pseudobulbs may be long and cylindrical or short and globose. Leaves vary from flat to almost terete in cross section. Sometimes the pseudobulbs and leaves are very small on exposed plants and all that is visible is a mass of flowers protruding from a hidden plant beneath. Occasionally on these exposed forms, the sepals and petals are reflexed, similar to the habit of Dendrobium cyanocentrum. Another variable feature with this subspecies is the ovary cross-section which ranges from distinctly 5-ribbed (almost winged) to rather indistinctly triangular. This sometimes gives difficulty in use of the key.

The flower size ranges from 0.7 to 1.7 cm but once, on Mt. Murray in the Southern Highlands Province of Papua New Guinea, plants with considerably larger flowers, up to 2.2 cm long, were collected (Reeve 494). The ovary was distinctly 5-ribbed and the leaves narrow and grass-like which readily separated it from Dendrobium sulphureum. It is exceptions like these which make it difficult to construct clear cut keys, and serve as a reminder that one can always be sure to discover something new and unexpected when collecting in the remote parts of New Guinea.

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Dendrobium masarangense var. chlorinum (Ridl.) T.M.Reeve & P.Woods, Notes Roy. Bot. Gard. Edinburgh (1989, publ. 1990) 196.

Basionym: Dendrobium chlorinum Ridl.

Similar to subsp. masarangense and almost identical to var. theionanthum, even in the ovary cross-section, but distinguished by its distinctly hairy ovary. The hairs are simple to 2-armed, 0.5-2 mm long, soft and tend to lie flat and parallel to the surface of the ovary (at least on pressed and boiled up herbarium specimens). The degree of hairiness varies amongst the population.

(largely after Reeve & Woods, 1989)

Colours:

Flowers white, orange, yellow, yellowish green or greenish white, lip usually green, sometimes very dark, with yellow, orange or orange-red apex (or just below apex).
Whitish-flowers have been reported occasionally from high altitude so the differences with subsp. masarangense are minor. Subsp. theionanthum is commonly bright greenish-yellow with orange to red lip apex, or just below apex, but occasionally greenish white or orange forms are encountered. An orange form, with a very dark lip, has been recorded from the Vogelkop Peninsula of Papua (van Royen & Sleumer 7165, 7872 & 8002), and once from the Enga Province of Papua New Guinea (Reeve 160, possibly a natural hybrid with Dendrobium dekockii ).

Habitat:

Epiphyte usually on small twigs and branches in lowland, montane and subalpine forest, and in secondary vegetation. Altitude 300-3250 m.

Distribution:

Sulawesi, New Guinea, Bismarck Archipelago, Bougainville, Solomon Islands, Vanuatu, New Caledonia, Fiji

Distribution New Guinea:

Papua (Vogelkop Peninsula, Mt. Carstenz, Mt. Doorman, Mt. Wilhelmina area); Papua New Guinea (Sandaun, East Sepik, Western Highlands,, Madang, Morobe, Central, and East New Britain Prov.)

Map: Dendrobium masarangense Schltr., distribution map, redrawn from T.M. Reeve & P.J.B. Woods, Notes Roy. Bot. Gard. Edinburgh 46 (1989) 284, map 4.

Cultivation:

Intermediate growing twig epiphyte, requires light shade and frequent waterings, but strongly dislikes soggy conditions.
Dendrobium masarangense subsp. theionanthum is rather difficult to grow and it requires good drainage.

Flowering time in the wild:

Throughout the year, perhaps with a peak from October to December.

Literature:

Schlechter, R. 1934. Repert. Spec. Nov. Regni Veg. Beih. 74: t. 32, fig. 128.
Reeve, T.M. & P.J.B. Woods. 1990. Notes Roy. Bot. Gard. Edinburgh 46: 191, fig. 7, pl. 5.
Lewis, B. & P.J. Cribb. 1991. Orchids of the Solomon Islands and Bougainville: 186, fig. 43 k-t.

Notes:

Despite its very local name derived from the type locality, Dendrobium masarangense is in fact a widespread species, being distributed from Sulawesi (Indonesia) in the west to Fiji in the east. It also has a large altitudinal range from almost sea-level in Vanuatu up to the alpine zone in New Guinea.Subsp. masarangense is recognised mainly by its white flowers, usually with orange or yellow below the apex of the lip. The mentum is usually somewhat bent (more evident on dried specimens), and plants are often more lax in habit with less rigid leaves than subsp. theionanthum. However this is not a consistent feature.Subsp. theionanthum var. theionanthum is very widespread in New Guinea occurring throughout the island. The two subspecies are separated mainly on colour and attitudinal differences. Usually it grows above 1500 m, but it may occur at lower altitudes on mountain ranges near the sea, and down to 1100 m in the cooler south-eastern end of the Owen Stanley Range in Papua New Guinea.