Calanthe vestita Wall. ex Lindl.

Kurzweil, Hubert, 2010, A precursory study of the Calanthe group (Orchidaceae) in Thailand, Adansonia (3) 32 (1), pp. 57-107 : 63-64

1. Calanthe vestita Wall. ex Lindl.

Genera and Species of Orchidaceous Plants: 250 (1833); Hooker, Flora of British India 5: 852 (1890); Seidenfaden & Smitinand, The Orchids of Thailand – A Preliminary List, part III: 333 (1961); Seidenfaden, Dansk Botanisk Arkiv 29: 26 (1975); Seidenfaden, Opera Botanica 114: 89 (1992); Seidenfaden & Wood, The Orchids of Peninsular Malaysia and Singapore: 165 (1992); Comber, Orchids of Sumatra: 255 (2001); Pridgeon et al., Genera Orchidacearum 4: 125 (2005). — Preptanthe vestita (Wall. ex Lindl.) Rchb. f., Flore des Serres et des Jardins de l’Europe 8: 245 (1853). — Phaius vestitus (Wall. ex Lindl.) Rchb. f., Gardeners’ Chronicle 1867: 264 (1867). — Alismorkis vestita (Wall. ex Lindl.) Kuntze, Revisio Generum Plantarum 2: 650 (1891). — Type: Myanmar, Tavoy, Wallich s.n., Wallich’s Catalogue 7345 (holo-, K-LINDL).

MATERIAL EXAMINED. —? North-Eastern, Nong Khai, 28.XI.1987, Sukhakul sub Seidenfaden & Smitinand 9393 (C spirit); 26.XI.1984, 9508 (C spirit); 26.XI.1984, 9509 (C spirit); 23.XI.1987, 9592 (C spirit). —?South- Western , Kanchanaburi, XI.[year not given], Thaithong 779 ( BCU spirit). — Peninsular, Ranong, Khao Chang, 4.I.1929, Kerr 0679 (B, BK, C, K). — Peninsular, Ranong, Khlong Nang Yon, 25.II.1974, Geesink et al. 7605 (B, C, C spirit, K, L). — Peninsular, Ranong, 19.XII.1979, Jacobsen 117 (C spirit); Seidenfaden & Smitinand 6101 (C spirit). — Peninsular, Phangnga, Khao Phra Mi, 9.I.1966, Hansen & Smitinand 11867 ( BKF, C). — Peninsular, Phangnga, Nang Yon, 23.XI.1973, Santisuk 668 ( BKF). — Peninsular, Phangnga, Ko Ra, 3.I.1974, Seidenfaden & Smitinand 6583 (C spirit). — Without locality, 26.XI.1997, Nanakorn et al. 9981 ( QBG spirit); Seidenfaden & Smitinand 5869 (C spirit) .

ILLUSTRATIONS. — Seidenfaden & Smitinand, The Orchids of Thailand – A Preliminary List, part III: pl. XIV (s.n.) (1961); Seidenfaden, Dansk Botanisk Arkiv 29: fig. 9a-c, pl. IV (1975); Seidenfaden & Wood, The Orchids of Peninsular Malaysia and Singapore: fig. 71a, b, pl. 9a (1992); Comber, Orchids of Sumatra: pl. on page 255 (2001); Pridgeon et al., Genera Orchidacearum 4: fig. 264.2A-J, pl. 36 (2005).

DESCRIPTION

Usually epiphytic herbs, occasionally epilithic, very rarely terrestrial, deciduous, 43-76(-125) cm tall. Basal sheaths not seen. Pseudobulbs conspicuous, ovoid, conical, covered by greyish-silvery leaf sheaths, 7-10 × 2-2.5 cm, glabrous, close together, several-noded with the largest part made up of a single internode. Leaves 1-4, annual and usually not present at the flowering time, lanceolate-elliptic, acuminate, 28-45 × (4.6-) 7.6-12 cm, glabrous; petioles 4-5 cm long. Inflorescences arising from the base of the pseudobulb, usually erect at the base and nodding in the upper part, much longer than the leaves (if present), softly pubescent; peduncles 27-52 cm long; sterile bracts 3-7, scattered along the flowering stem and a few clustered at its base, erect to suberect or spreading, lanceolate-oblong, acute or acuminate, 2.1-4.7 cm long, sparsely pubescent, sheathing; raceme lax, 7- to 15-flowered; rachis 16-30(-40) cm long; floral bracts persistent, broadly ovate-lanceolate, acuminate, 16-30 × 5-12 mm, much shorter than the pedicel plus the ovary, pubescent. Flowers to 55 mm across, white or cream and usually with yellow or more rarely red lip base. Ovary indistinguishable from the pedicel, 35-54 mm long, straight, densely pubescent. Sepals obovate-elliptic, acuminate to apiculate, indistinctly 5- or 7-veined, pubescent especially on their outside; median sepal 20-30 × 7-12 mm; lateral sepals oblique, 21-30 × 7-9.3 mm. Petals obovate-elliptic, obtuse, apiculate, indistinctly 3- to 7-veined from the base, 22-27 × 9-11 mm, glabrous. Lip 3-lobed, 24-32 × 19-36 mm, base completely united with the gynostemium, softly pubescent on the outside base and otherwise glabrous, often with a small auricle on each side where the lip is joined onto the gynostemium, spurred; midlobe bipartite, 10- 14 × 17-24 mm, sinus obtuse and often with a tiny tooth, each lobule spreading, oblong, obtuse; side lobes oblong, obtuse, 9-15 × 8-12 mm, not much widening towards the apex, spreading and pointing forwards; lower part of the disk with three longitudinal keels, area around these keels with short scale-like hairs; spur cylindric, softly pubescent, 20-30 mm long, pointing backwards at the base and strongly curved forwards above. Gynostemium 10-12 mm long, glabrous or sparsely pubescent; rostellum bilobed. Fruits not seen.

DISTRIBUTION AND PHENOLOGY

This species is quite rare in Thailand. All confirmed records come from the Ranong-Phangnga area in the northern parts of the Thai Peninsula and from adjacent islands, and in addition there are a few doubtful records from the North-East and South- West. Generally widespread in SE Asia, ranging from Myanmar to Indochina and the whole of the Malay Archipelago as far east as New Guinea. Found mostly as an epiphyte in evergreen forest, often found associated with limestone, from sea level to about 60 m. Flowering mainly from November to February .

REMARKS

Calanthe vestita has attracted much attention among orchid growers and has given rise to many hybrids. The species can easily be recognized by its large white or cream-coloured flowers with yellow or red markings on the lip base, the deeply bilobulate lip midlobe and the spreading lip side lobes.

Calanthe vestita is interesting from a habitat-ecological point of view as it is the only Thai species in its genus which is predominantly epiphytic. Having prominent pseudobulbs the species is well adapted to a climate with a pronounced dry season.

The collection Thaithong 779 from Kanchanaburi is unusual in the small size of the tepals, in the lip that lacks any ornaments and in its flowering time in November. Four collections from Nong Khai Province (Sukhakul sub Seidenfaden & Smitinand 9393, 9508, 9509, 9592) are largely intermediate in their flower size between C. rubens and C. vestita though approaching the concept of the latter species in its current delimitation ( Table 1). Flowers are white with pink lip base in 9393, white with light purple lip base in 9508, white with dark purple lip base in 9509 and pure white in 9592. In the spirit jars of these four collections and in letters found in the Seidenfaden working files they are variously referred to C. rubens and C. vestita . The specimens are here interpreted as unusual forms of C. vestita although the identification is uncertain. Apart from the morphological similarity this identification is also more likely from a phytogeographical point of view as C. vestita has been reported in neighbouring Laos ( Schuiteman et al. 2008).