Calanthe simplex Seidenf.

Kurzweil, Hubert, 2010, A precursory study of the Calanthe group (Orchidaceae) in Thailand, Adansonia (3) 32 (1), pp. 57-107 : 82-83

16. Calanthe simplex Seidenf.

Dansk Botanisk Arkiv 29: 42 (1975) ; Chen et al., Flora of China, vol. 25: 299 (2009). — Type: Thailand, Chiang Mai Province, Doi Chiang Dao , 21.XII.1931, Put 4470 (holo-, K!; flower from holo-, C spirit!).

ADDITIONAL MATERIAL EXAMINED. — Northern, Chiang Mai, Doi Chiang Dao, Baramee s.n. ( BCU spirit 009884); 7.XII.1985, Kurzweil 665 (K); 10.XI.1995, Maxwell 95-1148 (C, C spirit, CMU [Sc], CMU [Sc] spirit, L); 16.XII.1997, Nanakorn et al. 10199 ( QBG spirit); XI.[year not given], Suddee et al. 2456 ( BKF spirit); Suksathan s.n. ( BCU spirit 009016) .

ILLUSTRATIONS. — Seidenfaden, Dansk Botanisk Arkiv 29: fig. 16a, b (1975).

DESCRIPTION

Terrestrial herbs,apparently evergreen, 40-55(-94)cm tall. Basal sheath 1, linear, c. 12 × 1-1.5 cm, apparently fresh. Pseudobulbs inconspicuous, enclosed by the leaf sheaths, 4.5-8.5 × 1-1.5 cm, close together, several-noded.Leaves 2-3, lanceolate-oblong, acute, acuminate, 20-60 × 3.2-10.5 cm, glabrous; with petioles 7-15 cm long. Inflorescences arising from the base of the leafy shoot, densely hirsute, dull dark violet; peduncles 30-36(-75) cm long; sterile bracts 4-6, erect or suberect, scattered along the flowering stem and a few clustered at its base, lanceolate-oblong, acute, (1.1-) 1.9-4.1 cm long, sparsely hirsute, sheathing or not; raceme lax or semi-dense, 12- to 30-flowered; rachis 10-19 cm long; floral bracts persistent, ovate-lanceolate, acute, acuminate, 15-23 × 3.5-6 mm, longer than the pedicel plus the ovary, hirsute. Flowers: perianth and gynostemium light yellow-green, operculum cream; all perianth lobes hirsute on the outside. Ovary 6-9 mm long, distinct from the 5-9 mm long pedicel, both light green with violet tinge, densely pubescent. Sepals ovate-lanceolate, acute, shortly acuminate, 5-veined, 9-14 × 4.5-7.8 mm. Petals obovate-elliptic, sometimes slightly clawed, 3-veined, 8-12 × 2.5-5.3 mm. Lip unlobed, broadly reniform, 10-15 × 8-16 mm, base completely united with the gynostemium, spurred, marginally undulate or irregularly and rather coarsely dentate, apex often emarginate; callus as three basal keels; spur cylindric, straight, 8-12.5 mm long, sparsely hairy. Gynostemium 4-8 mm long, with stiff hairs. Fruits not seen.

DISTRIBUTION AND PHENOLOGY

In Thailand only known on the Doi Chiang Dao mountain massif in Chiang Mai Province in the North.The species was previously considered endemic to Th ailand, but is listed in the Flora of China (Chen et al. 2009) as occurring in S China (Yunnan). The

respective specimens were not seen in the present study, but according to the description the plants clearly match the Thai specimens of Calanthe simplex . In Thailand found in rugged limestone terrain in disturbed open forest or in savanna from 1700 to 1850 m. Flowering in November and December.

REMARKS

A distinct species with small or medium-sized yellow-green flowers with unlobed lip and strongly hairy gynostemium.In his description, Seidenfaden (1975) pointed out similarities with the Burmese C. wardii W.W.Sm. (now included in C. whiteana King & Pantl. ), from which it differs by strongly hairy sepals and petals and the stiff hairs on the gynostemium. Calanthe wardii also differs by having strongly developed calli at the spur entrance which are not found in C. simplex .

Based on the poor material that was available at the time Seidenfaden (1975) provisionally referred this species to subgenus Preptanthe , but a recently collected specimen with well-developed leaves and obscure pseudobulbs (Maxwell 95-1148) indicates that the species should be placed in section Calanthe .