299. EPIGENEIUM TRIFLORUM var. ORIENTALE, Orchidaceae

Jeffrey Wood

Summary. The history, taxonomy, distribution, ecology and cultivation of the Javan E’igeneium tnzomm var. orientale (Orchidaceae) are discussed; a full botanical description and a diagnostic key to the three varieties are provided.

Epkeneium, a genus closely related to Dendrobium, contains some 36 species distributed in China (Sichuan), Nepal, Bhutan, India, Myanmar (Burma), Indochina and Thailand south to Malaysia and Indonesia, and eastwards to Taiwan and the Philippines. The greatest concentration of species is found in Indochina, Sumatra and Borneo. The genus, which is still in need of a modern monographic treatment, has a complex history which is outlined below.

John Lindley, writing in Paxton’s Flower Garden for 1850, proposed the name Sarcopodium for a group of six taxa earlier referred to Bulbophyllum and Dendrobium. In a fuller treatment published in 1853 he listed 16 taxa, splitting them into two sections. The 12 taxa listed in the second of these sections are by common consent included within Bulboplylhrn today. The remaining four have been considered by many authors as representing a section within Dendrobium. Only Dendrobium amplum Lindl. ex Wall. was listed among these four when Lindley established Sarcopodium in 1850 which, accordingly, must be considered the type species of the genus. Joseph Hooker (1 890) considered Sarcopodium to be congeneric with Dendrobium, a position followed by several authors, some quite recently. Rolfe (1 9 lo), however, took the view that they formed a distinct group, albeit allied to Dendrobium, and accepted Lindley’s epithet; he added several new taxa to make a total of 21. Fritz Kraenzlin (1910) likewise accepted this view and also undertook several transfers, Unaware of Rolfe’s earlier paper; his list contained 20 taxa.

Epkeneium was established by Franqois Gagnepain (1 932) based on Dendrobium fargesii Finet from China; he recognized four taxa. Kraenzlin placed D. fargesii in Desmotrichum and this was never included by Rolfe in his list of Sarcopodium. Tang & Wang (1951, 195 1 a) transferred Gagnepain’s four taxa to Sarcopodium, treating EPkeneium and Sarcopodium as congeneric. Alex Hawkes (1 956) Pointed out that the name Sarcopodium Lindl. is a later homonym of Sarcopodium Ehrenb. ex Schltdl., a genus of fungi. He therefore

Bentham-Mown Trust 1996. Published by Hlackwcll Publishers, 108 Cowlcy Road, oxford OX4 IJF, UK and 298 Main Smct, Cambridge, MA 02142, USA. 139

proposed the new name Katherinea in honour of his mother Katherine H. Chatham for the orchid genus, as emended by Kraenzlin & Rolfe, and which he maintained as distinct from Dendrobium; 28 new combinations were made in Katherinea. Unfortunately, Hawkes had overlooked Tang & Wang’s earlier paper as pointed out by Summerhayes (1 957) who accepted the treatment proposed by ihe Chinese. He accordingly found that Gagnepain’s Epigeneium must have priority over Katherinea and undertook the necessary transfers, pointing out that Dendrobium fargesii should be the type species of the genus.

The views of Tang & Wang and of Summerhayes have been largely accepted by most subsequent authors. Balakrishnan & Chowdhury (1 966), however, maintained, after study of the type species of Epigeneium and Sarcopodium, that the two genera were distinct and returned to Katherinea for some of Lindley’s Sarcopodium. Their study is, unfortunately, based on only 5 northern species and no views are included on the placement of the numerous other taxa proposed for inclusion in Epigeneium and Katherinea. There is, however, a trend, as Seidenfaden (1 980) points out, toward a small grouping of species with one-leaved pseudobulbs and solitary flowers related to E. fargesii, for example E. longwepens (Ames & C. Schweinf.) Seidenf from Borneo. A slightly larger grouping contains species with two-leaved pseudobulbs and solitary flowers related to E. amplum, such as E. pulchellum (Ridl.) Summerh. from Sumatra. Over half of the taxa that have been placed within Epigeneium, however, have two- to three-leaved pseudobulbs and two- to many-flowered short to elongate inflorescences, including E. triiorum figured here. These are quite different from either of the above groups. Anomalies also exist in details of floral morphology, and it may be that after a critical monographic study, an argument for keeping Epigeneium separate from Sarcopodium may emerge. If this were so, Katherinea would then be the legitimate name for Sarcopodium Lindl. pro parte and the numerous transfers proposed by Summer- hayes would have to be rejected!

Generic circumscription is a matter of personal judgement and a subject of universal disagreement among taxonomists. Certainly, the polymorphic genus Dendrobium has now reached unwieldy proportions with upwards of 1400 species. Unfortunately, general principles for the evaluation of generic delimitation in the subtribe Dendrobiinae have yet to be developed. However, it would seem

140 0 Benthm-Moxon Trust 1996.

Epigeneium trgorurn var. orientale

Plate 299

HELEN GREENOP

justifiable, on the grounds of sheer practicality alone, to define certain homogeneous sections such as Diplocaulobium, Epigeneium and Flickingeria for recognition at generic level.

The taxa attributed to Epigeneium can be separated from Den- drobium on their habit of growth. The rhizomatous part of the shoot is very elongated and creeping, never abbreviated, and bears one- noded pseudobulbs producing one, two, or rarely three leaves. The inflorescences are terminal or pseudoterminal, a character not exclusive to Epigeneium, but shared with only a very few species of Dendro 6 ium .

Most Epigeneium are epiphytes of hill and mountain forest and shrubbery, often growing on exposed ridge tops. They prefer to grow among the canopy branches where light levels are high, often continuing to thrive in full sunlight on dead trees. Others grow at lower altitudes, sometimes scrambling on the forest floor, such as E. speculum UJ.Sm.) Summerh. from Borneo, which often occurs in open kerangas forest developed over nutrient-poor podsolic soils.

Very few species of Epigeneium are at all common in cultivation, although many growers will be familiar with the beautiful pink- flowered E. treacherianum (Rchb.f. ex Ho0k.f.) Summerh. [syn. E. bonii (Ames) Summerh.] from Borneo and the Philippines. Many of the other species would, I think, be desirable to breeders since they are generally very free flowering and have elegant flowers which are long lasting. Only three species have been figured previously in the Botanical Magazine: E. acuminatum (Rolfe) Summerh. (t.9 19 l ) , E. 9- mbidioides (Blume) Summerh. (t.4755) and E. treucherianum (t.659 1).

The Javan E. tnjorum, featured here, is sometimes confused with the related E. cymbidioides, which also occurs in Sumatra. This, however, can be distinguished by its broader, oblong or ovate leaves and obtuse sepals, and is generally more plentiful above 2000 m than below. Epigeneium trgflarum is a very variable species, endemic to the mountains of Java from where three varieties are currently recogn- ized: var. tnyorum, var. elongatum (Blume) J.B. Comber and var. orientale U.J.Sm) J.B. Comber (Comber, 1990). These may be distinguished using leaf length, inflorescence position, flower number, sepal width, and the length and location of the rib-like keels on the lip. It is var. orientale which is the subject of this plate. The specific epithet is a misnomer since all three varieties have usually more than three flowers per inflorescence. The following key to the varieties is adapted from that of Comber (1 990).

0 Bentham-hloxon Trust 1996. 141

Key to the varieties of Epigeneium triflorum 1. Lateral sepals distinctly broader than the dorsal sepal; lip with three

short distal keels alongside one another, the central keel longest, and three shorter ones near the base .................................. var. elongatum

1. Lateral sepals scarcely if at all broader than the dorsal sepal; lip with two short distal keels, and with three located further back, the outermost of which are sometimes further divided ................................................. 2

2. Leaves (6.5-) 14-2 I(-30) cm long; inflorescences pendulous, with 6-1 7 flowers; pseudobulbs (2-)4-7 cm long, borne (2-)4-8 cm apart on rhizome ....................................................................... var. orientale

2. Leaves up to 12 cm long; inflorescences borne horizontally, with 2-6 flowers; pseudobulbs about 2 cm long, borne 2-3 cm apart on rhizome

var. triflorum

Variety orientale is perhaps the finest, the pendulous inflorescences bearing up to as many as 17 flowers which open all together. Comber (1 990) comments that it is very common on almost every mountain in East Java and also on Gunung Slamat in Central Java. Plants are usually found growing in bright light high u p on branches, or more rarely as a trunk epiphyte on isolated trees.

The plant illustrated here was donated to Kew in May 1948 by T. Winchcombe of Swansea Parks Department, and continues to flower regularly.

CULTIVATION by Sandra Bell. Although this specimen of Epigeneium tnyorum is by no means our oldest orchid resident, some of which came into the collection during the last century, its presence through nearly fifty years bears ample testimony to its adaptability, vigour and longevity. It has proved to be very amenable to cultivation, flowering profusely every January in its present position. Coming as it does from altitudes of 1000 m or more in Java, we find that a glasshouse night minimum temperature of 17°C is suitable, with day minima of 20°C and 22°C in winter and summer respectively. The temperature rarely rises above 28°C except on the hottest days of summer. Overnight, the relative humidity is maintained at about 85% and is then allowed to fall to 75% by mid afternoon. Although Comber repeatedly found E. tnfrorum growing in sun we find that under glass a rather more shady position is required. It faces eastwards, receiving at most an hour or two of sun in the early morning. A 60% shade cloth covers the glasshouse from April until September.

During the last few years E. tnjorum has been grown in pots containing a medium grade, bark-based orchid medium; however,

142 0 Iknthun-Moxon Trust 1996.

since it has a relatively fine, shallow root system, it is currently grown mounted on cork oak. It seems to thrive provided that suitable environmental conditions are maintained. Daily care consists of a heavy misting with water in the morning and again in the afternoon and the application of a weak, liquid fertilizer each week while the plant is in growth.

Epigeneium trgorum has not been grown from seeds at Kew since it is readily propagated vegetatively by backbulbs or division, during the spring.

Epigeneium triflorum (Blume) Summerh. var. onentale (JJ.Sm.) J.B. Comber, Orchids ofJava: 246 (1990). Type: East Java: Loemadjang, ?Smith (BO, holotype). &t&obium elongatum Lindl. var. orientale JJ.Sm. in Bull. Dtp. Agric. Indes

NCerl. 43: 52 (19101. DESCRIPTION. Epiphytic herb. Rhizome creeping, up to 50 cm long, up to

0.9 cm in diameter, with a few short branches, broadest below pseudobulb, greyish-brown. Roots flexuous, branching, smooth, 1 mm in diameter. Cataphylls 4 or 5, ovate-elliptic, obtuse to subacute, 1-6 cm long, per- gamaceus, becoming split by the developing pseudobulbs and eventually disintegrating, purple-green when emerging, turning fawn to chestnut- brown. Pseudobulbs 1 -noded, bifoliate, borne (2-)4-8 cm apart, ovate to ovate-elliptic, with 4 to 8 obtuse angles, (2-)4-7 X 1.5-3 cm, glossy olive- green, turning yellowish-brown and stained reddish-brown with age. Leaves erect or gently curving, oblong to ligulate, attenuated, cuneate and conduplicate below, apex shortly unequally bilobed, (6.5-) 14-2 1(-30) X (1-)1.5-2(-2.5) cm, texture thin and coriaceous, with 3 major secondary nerves either side of mid-nerve, mat mid olive-green above and below, mid-nerve and margin appearing pale and translucent when held to the light. InJErescence terminal, borne at apex of pseudobulb between leaves, mostly pendulous, bearing 6- 17 flowers borne 1-1.3 cm apart, all opening simultaneously; peduncle 11-13 cm long; non-floriferous bracts 3 or 4, ovate-elliptic, acute, tubular, 0.5-2 cm long, remote, dark brown; rachis slender, 6-13 cm long; floral bracts ovate, acute, 4-7 mm long. Flowers unscented, pedicel and ovary cream, sepals and petals cream to white, lip cream or white, finely spotted red in the basal two-thirds, side lobes with denser red markings, mid-lobe golden-yellow proximally, cream or white distally, keels creamy-white. Pedicel and ovary narrowly cylindrical, about 2 - 2 4 cm long, straight or gently curved. Sepals andpetals spreading, with 7 or 8 main nerves. Dorsal sqal oblong-elliptic, acute or subacute, 1.7-2.3 X 0.6-0.7 cm. Lakral sepals obliquely oblong to oblong-elliptic, acute or subacute, 1.6-2.2 X 0.7 cm. Petals narrowly spathulate-ligulate, acute or subacute, 1.9-2.7 X 0.4-0.45 cm. Lip 3-lobed, movably attached to column foot, 1.3-1.5 cm, long; side lobes erect, obliquely triangular, rounded to subacute, 1-1.1 cm long, 0.5 cm high; mid-lobe triangular-ovate, acute,

0 Bcntham-Moxnn Trus 1996. 143

Epie;eneium triflo-var. orientale. A, dorsal sepal, X 2; B, lateral sepal, X 2; C, petal, X 2; D, lip and column, side view, X 3; E, lip, X 3; F, column apex with anther-cap, X 4; G , ,other-cap, front view, X 10; H, pollinia, X 4. Drawn by Helen Greenop.

recGrved, 0.4-0.5 X 0.5-0.7 cm; disc with 2 fleshy, knob-like distal calli, and 3 narrow, less prominent fleshy proximal keels commencing from the bas& and terminating just behind distal calli, sometimes the outer keels fur&er divided or forming 2 additional keels. Column porrect, gently

shallowly concave, 0.9-1 X 0.35 cm, apex narrowed and shortly rostrate, foot at right angles to the ovary, 0.5 cm long; anther-cap ovate- cuc~l la te , rounded, base truncate, 2-2.1 X 2 mm, smooth.

DISTRIBUTION. Indonesia: Java; 1000-1680 m. P~~ENOLOGY. Flowering recorded in May, June and August.

REFERENCES

Balakrishnan, N.P. & Chowdhury, S. (1966). Notes on orchids of Bhutan 1 Epigeneium Gagnep. and Katherinea Hawkes. Bulletin of the Botanical selruey ofIndia 8, 3 & 4: 312-318.

C o ~ b e r , J.B. (1990). Orchids of Java. Bentham-Moxon Trust. Royal Botanic Gardens, Kew.

0 ~enthun-Maxon Trust 1996. 144

Gagnepain, F. (1 932). Huit genres nouveaux d’orchidtes Indochinoises.

Hawkes, A.D. (1956). Katherinea, a new name for the orchid genus

Hooker, J.D. (1890). The Flora OfBritish India 5: 667-858. Kraenzlin, F. (19 10). Orchidaceae - Monandrae - Dendrobiinae, part 1 in

Engler, A. (ed.). Das PJEnzenreich IV, Heft 45: 1-382. Lindley, J. (1 850). Sarcopodium lobbii (alias Bulbophyllum lobbii Lind-

ley). Paxton’s Flower Garden 1: 154-155, gleanings and original mem- oranda no. 199.

Bulletin du Museum d’Histoire Naturelle, Paris, skr. 2 , IV, 5: 59 1-60 1.

Sarcopodium. Lloydia 19,2: 94-98.

Lindley, J. (1 853). Sarcopodium. Folia Orchidacea, part 2: 1-6. Rolfe, R.A. (191 0). The Genus Sarcopodium. Orchid Review 18: 237-240. Seidenfaden, G. (1 980). Orchid Genera in Thailand IX. Flickingeria

Hawkes and Epigeneium Gagnep. Dansk BotaniskArkiv 34, 1: 1-104. Summerhayes, V.S. (1957). Notes on Asiatic Orchids 11. Kew BuZLetin 12:

Tang, T . & Wang, F.T. (1951). Contributions to the knowledge ofEastern Asiatic Orchidaceae 11. Acta Phytotaxononica Sinica 1, 1 : 23- 102.

Tang, T . & Wang, F.T. (1951a). O n the identity of eight Gagnepain’s orchidaceous genera from Indochina. Acta Scientia Sinica 2, 3: 3 12-322.

2 59-268.

0 Hcnthnm-Moxon Trust 19%. 145