Dendrobium vexillarius J.J.Sm., Bull. Dép. Agric. Indes Néerl. 39 (1910) 12; Nova Guinea 8, 3 (1911) 575, t. 96A.
Type: Römer, von 1294; 1297 (New Guinea) (syn BO).
Erect to suberect, occasionally pendulous, tufted epiphyte or terrestrial, 3-25(-40) cm high. Roots 0.5-2 mm diameter. Rhizome short. Pseudobulbs 0.5-30 by 0.2-1.5 cm, ovoid, obclavate to cylindrical, tapered gradually towards apex, few to many noded (up to 20), upper half with 2-10 leaves. Leaves 1-16(-24) by 0.2-1.8 cm, erect to spreading (to pendulous), linear, linear-lanceolate to elliptic, acute to obtuse, usually mucronate, sheaths usually persistent. Inflorescences arising terminally or laterally from both leafy and leafless stems, often several arising together from the same node, (1-)2-5(-7)-flowered, peduncle to 1 cm long, rachis to 2 cm long; bracts large, to 3.5 cm long, ovate-triangular, keeled and laterally compressed, apex acute to acuminate-subulate. Flowers 2.2-5 cm long, usually widely opening, to 4.25 cm broad, long lasting (c.6 months). Median sepal 7-20 by 3.5-9 mm, ovate to oblong-elliptic, obtuse to subacute, ::L mucronate, keeled. Lateral sepals 19-45 by 5-13 mm, obliquely triangular to ovate-triangular, obtuse to abruptly acuminate, mid-vein often strongly crested on outside, keels to 2.5 mm high towards pointed apex; basal fused part 3-8 mm long, conical to subconical; mentum total length 14-30 mm, tip usually bilobed. Petals 7-20 by 2.5-9 mm, obliquely oblong-obovate to subspathulate, sometimes subrhombic, obtuse to acute or apiculate. Lip 18-39 by 3-7 mm, subtrilobate, sublinear, adnate to column foot at base, upper margins incurved, without a cross-ridge, small side lobes rounded, apex triangular, acute to subacuminate, usually recurved, sometimes rolled under. Column 2.5-5.5 mm long; foot 14-30 mm long, nectary near base indistinct; anther 2.5-4.5 mm broad; pollinia 1.5-2 mm long. Ovary 3-winged, sometimes with small lateral ribs, dorsal wing usually projecting up behind dorsal sepal, apex pointed; pedicel and ovary 16-40 mm long. Fruit c. 30 by 14 mm, ovoid.
(after Reeve & Woods, 1989).
Colours: Roots white with green tips. Leaves green to dark purplish, occasionally red (underside more often coloured), sheaths becoming greyish white, sheaths and leaves sometimes finely purple spotted (var. uncinatum ). Flowers red, orange, yellow, whitish, greenish, blue-green, blue, bluish-grey, grey, violet, purple, purple-red or pink, lip green to almost black, apex usually red or orange or bi-tri-coloured with orange to yellow band below tip, ovary green to purplish or violet.
Habitat: Epiphyte or terrestrial in montane and alpine forests, shrubberies and grasslands. Altitude (?850-) 1200 to 3500 (-4000) m.
Flowering time in the wild: Throughout the year.
Distribution: Moluccas, New Guinea, Bismarck Archipelago.
Distribution in New Guinea: See under the varieties.
Maps: VEXI1MAP.JPG [Dendrobium vexillarius J.J.Sm. (vars. vexillarius, microblepharum & albiviride) distribution map, redrawn from T.M. Reeve & P.J.B. Woods, Notes Roy. Bot. Gard. Edinburgh 46 (1989) 289, map 17]; # VEXI2MAP.JPG [Dendrobium vexillarius J.J.Sm. (vars. retroflexum, uncinatum & elworthyi) distribution map, redrawn from T.M. Reeve & P.J.B. Woods, Notes Roy. Bot. Gard. Edinburgh 46 (1989) 290, map 18.]
Notes: Dendrobium vexillarius is the most common of all the 'Oxyglossum' species in New Guinea and has a wide range of habitats and colour forms.
Dendrobium vexillarius is similar to the other larger-stemmed species Dendrobium nebularum and Dendrobium pentapterum but is readily distinguished from both of them by its 3-winged ovary.
Various entities are recognised within this complex species, some more clearly defined than others, and Reeve & Woods (1990) have been able to distinguish six varieties. These varieties represent fairly distinct populations in the wild, and although there are other differences, the varietal key is conveniently based on the colour of the flowers. There is some overlap, particularly with the yellow-flowered forms and there may be difficulty with preserved specimens for which there are no records of colour, but the key should be fairly workable for the large majority of plants collected in the field or in cultivation.
(after Reeve & Woods, 1989).
Cultivation: Cool growing epiphyte, keep in shade.
INFRASPECIFIC TAXA
Key to varieties (in New Guinea):
1a. Mature plants small, pseudobulbs less than 2.5 cm long (flowers orange to orange-red) ... Dendrobium vexillarius J.J.Sm. var. elworthyi T.M.Reeve & P.Woods
1b. Mature plants with pseudobulbs over 2.5 cm long ... 2.
2a. Flowers orange, orange-red or orange-yellow ... Dendrobium vexillarius J.J.Sm. var. microblepharum (Schltr.) T.M.Reeve & P.Woods
2b. Flower colour otherwise ... 3.
3a. Flowers greenish blue, blue, bluish-grey or grey, often suffused with violet ... Dendrobium vexillarius J.J.Sm. var. retroflexum (J.J.Sm.) T.M.Reeve & P.Woods
3b. Flower colour otherwise ... 4.
4a. Leaves linear to linear-lanceolate, mostly less than 6 mm, broad (flowers yellow or greenish yellow) ... Dendrobium vexillarius J.J.Sm. var. vexillarius
4b. Leaves linear-lanceolate, to elliptic, mostly over 6 mm, broad ... 5.
5a. Flowers whitish green to primrose yellow, mostly over 3.5 cm long (high altitude variety from Owen Stanley Range, SE New Guinea, 2600-3400m) ... Dendrobium vexillarius J.J.Sm. var. albiviride (P.Royen) T.M.Reeve & P.Woods
5b. Flower colour otherwise (or if yellow, then from below 2500m and flowers mostly less than 3.5 cm long) ... 21c. Dendrobium vexillarius J.J.Sm. var. uncinatum (Schltr.) T.M.Reeve & P.Woods.
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Dendrobium vexillarius J.J.Sm. var. vexillarius.
Var. vexillarius is recognised by its narrower linear to linear-lanceolate leaves, usually all less than 7 mm; wide; flowers 2.5-4.2 cm long.
Colours: Leaves often purple and green to dark purple. Flowers yellow to greenish yellow.
Habitat: Epiphyte in montane and alpine forest, often on small branches and twigs high up on Nothofagus, rarely terrestrial (in Wau area recorded as low epiphyte and terrestrial). Altitude 2000 to 3500 m.
Distribution: New Guinea.
Distribution in New Guinea: Papua (Mt. Carstenz, Mt. Doorman, Mt. Trikora, Lake Habbema); Papua New Guinea (Sandaun, Enga, Southern Highlands, Western Highlands, Chimbu, Eastern Highlands, Madang, Morobe, Central and Milne Bay Provinces).
Notes: Var. vexillarius is mainly confined to the alpine zone, above 3000 m, and is quite common in some localities. However it does extend lower than this, usually to about 2500 m, but in the Wau area, on the Edie Creek road, there is (or was) a colony at 2000-2200 m.
As noted above, the narrow leaves are the most distinctive feature of this variety, together with the colour of the flowers which is always yellow to greenish yellow.
J.J.Sm. labelled Lam 1591 & 1655 from Mt. Doorman as var. 'purpureoviride' but later changed his mind and did not publish this name. These particular specimens were collected at 3500 m and the purple colouration in the leaves indicates that it grew in an exposed position. Reeve has often observed leaves on this variety tinged dark purple during his collecting patrols in Papua New Guinea.
Var. vexillarius is particularly common as a high epiphyte on Nothofagus in the Enga Province above 2800 m: Reeve has counted well over a hundred plants on the small branches and twigs of a fallen tree. On Mt. Giluwe in the Southern Highlands Province this variety is also common on Papuacedrus papuana, the so-called 'New Guinea Pine'.
Cultivation: Difficult, as it requires high humidity and low temperatures.
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Dendrobium vexillarius J.J.Sm. var. retroflexum (J.J.Sm.) T.M.Reeve & P.Woods, Notes Roy. Bot. Gard. Edinburgh (1989, publ. 1990) 251.
Basionym: Dendrobium retroflexum J.J.Sm.
Var. retroflexum is recognised by its green, blue, bluish grey, or steel-grey flowers which are often tinged with violet, especially at mentum tip, ovary and tips of tepals, 2.5-4.5 cm long. Unlike other varieties, plants found in the wild in shaded habitats often have a semi-pendulous habit.
Colours: Flowers green, blue, bluish grey, or steel-grey flowers which are often tinged with violet, especially at mentum tip; rarely yellow.
Habitat: Low epiphyte embedded in clumps of moss in alpine shrubberies, often with semi-pendulous habit in forest. Altitude 2700 to 3450 m.
Distribution: New Guinea.
Distribution in New Guinea: Papua (Mt. Carstenz, Mt. Trikora, Lake Habbema, Star Mountains); Papua New Guinea (Sandaun, Enga and Southern Highlands Provinces).
Notes: The unusual colour of var. retroflexum attracts much attention when first encountered in nature or seen in cultivation. The colour of the flowers varies from a sea-green or bluish green to full blue, bluish grey to light silvery grey. The flowers are often tinged with violet, especially at the tips of the sepals and petals and on the mentum and ovary. The lip is very dark violet, almost black, with an orange-red to scarlet apex which is usually rolled over but occasionally is unbent (in which case it is often lighter in colour).
Very occasionally, a yellow form is seen amongst a large population, e.g. Reeve nos 121 & 1131, both from Enga Province. Unless detailed notes are recorded this uncommon form is very difficult to key out from some of the other varieties.
Cultivation: As for var. vexillarius.
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Dendrobium vexillarius J.J.Sm. var. uncinatum (Schltr.) T.M.Reeve & P.Woods, Notes Roy. Bot. Gard. Edinburgh (1989, publ. 1990), 253.
Basionym: Dendrobium uncinatum Schltr.
Var. uncinatum is recognised by its erect robust habit, wider lanceolate leaves over 7 mm; broad, and its carmine or crimson through purplish-red to pinkish-purple (cerise), occasionally yellow or greenish yellow, rarely white, flowers 2.5-4.5 cm long. Purple spotting is often present on the leaves, new sheaths and occasionally the flowers.
Colours: Flowers carmine or crimson through purplish-red to pinkish (cerise), occasionally yellow or greenish yellow, rarely white.
Habitat: Epiphyte in margins of primary forest, in secondary forest, on Cyathea in subalpine grasslands etc, occasionally terrestrial, usually growing in rather exposed positions. Altitude (? 850-1200-) 1600 to 2800 (-3000) m.
Distribution: New Guinea and possibly Moluccas.
Distribution in New Guinea: Papua (Vogelkop Peninsula, Mt. Doorman, Idenburg River); Papua New Guinea (Western, Enga, Southern Highlands, Western Highlands, Chimbu, Eastern Highlands, Madang, Morobe, Central and Milne Bay Provinces).
Notes: Var. uncinatum is the most common of the six varieties of Dendrobium vexillarius and has the widest distribution throughout mainland New Guinea. It is particularly common in many parts of the Highlands Region of Papua New Guinea, from about 1800 m to 2800 m.
The most common colour form is pinkish purple (sometimes described as cerise) which corresponds to Spiraea red on the Royal Horticultural Society's colour chart no. 25. It is a difficult colour to define exactly and the shade does vary. Plants growing in direct sunlight have brighter flowers.
There is a crimson form in Milne Bay Province recorded variously as bright crimson, raspberry-red or deep wine-red (Cruttwell 731, 772, 932 & 1242). Schlechter's colour descriptions for the types of Dendrobium uncinatum and Dendrobium trialatum, both from Madang Province, are given as 'pale carmine-red'.
Yellow flowered forms have been collected from time to time and are represented by Gibbs 5907, Doorman 14 & 15 and Brass 11883 from West New Guinea as well as Argent s.n. from Mt. Shungol in Morobe Province of East New Guinea. These have also been reported from Western Highlands Province as well as Enga Province. Reeve has also collected a whitish form from the Yonggamugl area of Chimbu Province.
The name Dendrobium uncinatum has been correctly applied to cultivated specimens of this variety for a long time. Previously the orange-red variety was exported from Papua New Guinea under this name, but it is now treated under var. microblepharum (q.v.).
In suitable habitats in the wild, e.g. when epiphytic on Cyathea in subalpine grasslands, var. uncinatum occasionally grows into very large clumps, over 20 cm across. Also at 2800 m in Enga Province, Reeve observed that this orchid sometimes survived the severe frosts of 1972 whilst other epiphytes, and occasionally the host tree were killed.
Cultivation: Prefers a more exposed and somewhat drier position than var. vexillarius. However, heat and prolonged drought invariably prove fatal.
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Dendrobium vexillarius J.J.Sm. var. microblepharum (Schltr.) T.M.Reeve & P.Woods, Notes Roy. Bot. Gard. Edinburgh (1989, publ. 1990), 255.
Basionym: Dendrobium microblepharum Schltr.
Var. microblepharum is recognised by its usually more slender stems, greater than 2.5 cm long on mature plants, and by its orange to orange-red or occasionally orange-yellow flowers 2.5-4 cm long.
Colours: Flowers orange to orange-red or occasionally orange-yellow.
Habitat: Epiphyte, usually low, in montane shrubberies and forest, sometimes on cultivated Cordyline. Altitude 1800-2900 m.
Distribution: New Guinea.
Distribution in New Guinea: Papua (Lake Habbema); Papua New Guinea (Sandaun, Enga, East Sepik and Southern Highlands Provinces).
Notes: Var. microblepharum is a very attractive orchid with bright clusters of sizeable orange to orange-red flowers, and is used for arm and hair adornment by natives of Enga Province, Papua New Guinea. This variety occurs in a small part of East New Guinea: mainly from Telefomin to Laiagam along the tributaries which form the upper catchment of the Strickland River.
Reeve has observed small populations separated from the main 'belt' and suspects that, because of its horticultural merit, natives have transported this variety to their own areas in the past. This could also account for its presence in the Tari District. There is a single recording from West New Guinea and further exploration is necessary before commenting on the extent of its western distribution.
Cultivation: As for var. uncinatum, perhaps requiring less light.
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Dendrobium vexillarius J.J.Sm. var. albiviride (P.Royen) T.M.Reeve & P.Woods, Notes Roy. Bot. Gard. Edinburgh (1989, publ. 1990) 257.
Basionym: Dendrobium albiviride P.Royen.
Var. albiviride is a high altitude variety recognised by its leaves over 7 mm; broad and its large whitish green to primrose-yellow flowers (3-)3.5-5 cm long.
Colours: Flowers whitish green to primrose-yellow.
Habitat: Low epiphyte in alpine shrubberies etc. Altitude 2600 to 3400 m.
Distribution: New Guinea.
Distribution in New Guinea: Papua New Guinea (Central and Milne Bay Provinces).
Notes: Var. albiviride is closely related to var. uncinatum, but grows at higher altitudes on the Owen Stanley range. In the Murray Pass area of Mt. Albert Edward it is a rather common low epiphyte from 2800 to 3400 m. Its stems are usually quite thick and it has larger flowers which are whitish green to yellow. In the opinion of Reeve & Woods (1990) these features warrant recognition at varietal level.
Cultivation: Probably as for Dendrobium brevicaule.
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Dendrobium vexillarius J.J.Sm. var. elworthyi T.M.Reeve & P.Woods, Notes Roy. Bot. Gard. Edinburgh (1989, publ. 1990) 258, fig. 29A2, B-H, pl. 16B.
Type: East New Guinea, Central Province, Kupiano District, Musa Mountains, Obaka Range (SE of Doma village in the Northern Province), c. 1200 m, 11 xi 1962, Woods 318 (holo E; iso AMES, K, L, LAE, NSW).
Erect to suberect epiphytic herb, 2-5 cm high. Pseudobulbs 0.5-2(-2.4) by 0.2-0.6 cm, ovoid, fusiform, to cylindrical, apex 2-3-leaved. Leaves 1-5 by 0.2-0.6 cm, linear-lanceolate to elliptic, mucronate. Inflorescences 1-2-flowered. Flowers (2-)2.2-3(-3.3) cm long; lip not recurved; ovary blackish.
Colours: Flowers orange or reddish-orange; lip usually purple or black with apex orange,.
Habitat: Epiphyte in elfin woodland amongst a rich epiphytic flora. Altitude 1100 to 2900 m.
Distribution: New Guinea.
Distribution in New Guinea: Papua New Guinea (Southern & Eastern Highlands and Central Provinces).
Notes: This variety was named in honour of Mr Geoffrey C. Elworthy whose influence, and interest in the orchids of the Central Province, initiated and supported the 1962 expedition to the Musa Mountains area by P. Woods. Mr Elworthy was a long-time resident of Papua and forwarded many plant specimens, mainly living, to the Botanic gardens at Lae, Edinburgh and Kew.
Cultivation: This has so far proved difficult. It requires excellent aeration and drainage.
(largely after Reeve & Woods, 1989)