Calanthe biloba Lindl.

Kurzweil, Hubert, 2010, A precursory study of the Calanthe group (Orchidaceae) in Thailand, Adansonia (3) 32 (1), pp. 57-107 : 82

15. Calanthe biloba Lindl.

Folia Orchidacea 6: 3 (1854) ; Hooker, Flora of British India 5: 848 (1890); Seidenfaden & Smitinand, The Orchids of Thailand – A Preliminary List, part III: 335 (1961); Seidenfaden & Smitinand, The Orchids of Thailand – A Preliminary List, part IV, 2: 793 (1965); Seidenfaden, Dansk Botanisk Arkiv 29: 12 (1975); Pearce & Cribb, Flora of Bhutan 3 (3): 284 (2002); Chen et al., Flora of China, vol. 25: 299 (2009). — Alismorkis biloba (Lindl.) Kuntze, Revisio Generum Plantarum 2: 650 (1891). — Type: India, Sikkim, 4000 ft, Hooker 246 (holo-, K!).

Calanthe biloba var. obtusata E.C.Parish & Rchb. f., Transactions of the Linnean Society of London 30: 144 (1874). — Type: Myanmar, Tenasserim, Parish 254 (holo-, K!).

Calanthe biloba var. diptera Hook. f., Flora of British India 5: 848 (1890). — Type: India, Naga Hills , Prain 72 (holo-, K!).

Calanthe biloba var. treutleri Hook. f., Flora of British India 5: 848 (1890). — Type: India, Sikkim, alt 6000 ft, Treutler 1155 (holo-, K!).

MATERIAL EXAMINED. — Northern, Chiang Mai, Doi Inthanon, 29.XII.1926, Garrett 362 (K); 19.XI.1930, 608 ( BKF, K). — North-Eastern, Loei, Phu Luang, Wichiansin s.n. ( BCU spirit 11056). — Without locality, Chueachan s.n. ( QBG spirit 17585); Thorut s.n. ( BCU spirit 6014) .

ILLUSTRATIONS. — Seidenfaden, Dansk Botanisk Arkiv 29: fig. 1a, b (1975).

DESCRIPTION

Terrestrial herbs, evergreen, 40-70 cm tall. Basal sheaths one to few, mostly decayed at the flowering time and only their veins remaining. Pseudobulbs inconspicuous and largely enclosed by the leaves, cylindric, 4-12 cm long, close together, severalnoded. Leaves 3-4, perennial, broadly elliptic, acute, acuminate, 12-40 × 4.6-10.3 cm, with undulate margins, glabrous; with grooved petioles to 15 cm long. Inflorescences arising from the base of the leafy shoot or in its basal part well above the ground, shortly pubescent; peduncles 20-35 cm long; sterile bracts 3-4, scattered along the flowering stem, erect or suberect, narrowly lanceolate, long-acuminate, 1-3.5 cm long, shortly pubescent, the lower sheathing; raceme erect, lax, few- to many-flowered; rachis 11-22 cm long; floral bracts persistent, narrowly lanceolate, acute, shortly pubescent, 9-20 × 1-3 mm, shorter than the ovary plus the pedicel. Flowers 20- 35 mm across, red-brown, yellow or violet-spotted, lip pale violet, spur pink. Ovary indistinguishable from the pedicel, 20-25 mm long, pubescent.Sepals oblong-elliptic, acuminate to caudate, 5-veined, 15-18 × 5-8.5 mm, glabrous or pubescent on the outside and sometimes slightly puberulous on the inside. Petals oblong-lanceolate, somewhat clawed, acuminate, 3-veined, 15-16 × 3-6 mm, glabrous. Lip 2-lobed, broadly ovate to reniform, 19-25 × 20- 26 mm, extensively united with the gynostemium, clawed, apically deeply incised, incision 5-6 mm deep and 8-10 mm wide, with a minute tooth in the middle, shortly spurred, erose or undulate on the margins; callus in the form of two obscure keels in the centre of the blade; spur conical, 2-4 mm long. Gynostemium 5-7 mm long, with a column-foot 2-6 mm long. Fruits ellipsoid, c. 30 × 15 mm.

DISTRIBUTION AND PHENOLOGY

In Thailand known from a few collections made in the North and North-East. Generally widespread on the Asian continent from the Himalayas to Myanmar and S China. The habitat ecology has not been recorded; collections were made at altitudes of between 1460 and 1550 m. Flowering in November and December.

REMARKS

A very distinct species with large flowers, short lip spurs and a clawed broadly reniform and apically incised lip.