Calanthe angustifolia (Blume) Lindl.

Kurzweil, Hubert, 2010, A precursory study of the Calanthe group (Orchidaceae) in Thailand, Adansonia (3) 32 (1), pp. 57-107 : 76-78

10. Calanthe angustifolia (Blume) Lindl.

Genera and Species of Orchidaceous Plants: 251 (1833); Hooker, Flora of British India 5: 854 (1890); Seidenfaden, Nordic Journal of Botany 6: 161 (1986); Comber, Orchids of Java: 92 (1990); Seidenfaden & Wood, The Orchids of Peninsular Malaysia and Singapore: 171 (1992); Comber, Orchids of Sumatra: 258 (2001); Chen et al., Flora of China Vol. 25: 295 (2009). — Amblyglottis angustifolia Blume, Bijdragen : 369 (1825). — Alismorkis angustifolia (Blume) Kuntze, Revisio Generum Plantarum 2: 650 (1891). — Type: Indonesia, Java, Buitenzorg, in mountain forest, Blume s.n. (not found).

MATERIAL EXAMINED. — Peninsular, Nakhon Si Thammarat (only photo seen). — Peninsular, Yala, Hala-Bala , 4.IX.2005, Poopath 369 ( BKF spirit) .

ILLUSTRATIONS. — Comber, Orchids of Java: pl. on page 92 (1990); Seidenfaden & Wood, The Orchids of Peninsular Malaysia and Singapore: fig. 74a, b (1992).

DESCRIPTION

(MAINLY AFTER THE THAI SPECIMEN)

Terrestrial herbs, evergreen, glabrous, c. 30 cm tall. Basal sheaths largely decayed at the flowering time, to 5.5 cm long. Pseudobulbs inconspicuous

and largely enclosed by the leaf sheaths, severalnoded, to 7.5 cm long, spaced on the rhizome 5-6.5(-9) cm apart; rhizome creeping, slender, with c. 2 cm long internodes. Leaves 3-6, perennial, linear-lanceolate, acute or acuminate, 18-50 × 1-3.75 cm; with grooved petioles to 14 cm long. Inflorescences erect, arising from the base of the leafy shoot; peduncle 15-23 cm long; sterile bracts 4, erect or suberect, lanceolate-oblong, acute, to 2.5 cm long, two of them at the stem base and the remainder scattered on the stem; raceme semi-dense or lax, c. 25-flowered; rachis 5-7.5 cm long; floral bracts caducous. Flowers white and usually with some yellow on the lip, callus deep yellow; not opening very widely. Ovary 6-8 mm long, distinct from the 6-7 mm long pedicel. Sepals ovate-elliptic, acute or acuminate, mucronate, 5-veined, 10-13 × 5-7 mm. Petals broadly ovate-elliptic, narrowed at the base, acute, 4-veined, 9.5-11 × 5.5-8 mm. Lip 3-lobed, to 12.5 × 7-8 mm, completely united with the gynostemium, spurred; midlobe obovate, apically deeply emarginate, 5-5.5 × 6.7-8 mm; side lobes erect, oval or rounded-square, 1.9-2.2 × 1.5-2.3 mm; callus as two short erect and triangular keels between the lip side lobes; spur clavate, 8-10 mm long. Gynostemium 4-6.5 mm long. Fruits not seen.

DISTRIBUTION AND PHENOLOGY

This species is widespread in SE Asia, ranging from western Malesia to Indochina and S China and has only recently been recorded in the extreme south of the Thai Peninsula. The only confirmed Thai specimen was growing in mountain forest near the summit at about 1440 m. Flowering in September. In the Malesian part of the distribution area the plants are found in moss forest and mountain forest up to 2000 m.

REMARKS

This is a new distribution record for Thailand. Calanthe angustifolia is distinct from all other Thai species in Calanthe sect. Styloglossum with its white flowers and the yellow on the lip, and also the apically deeply cleft lip with its two basal calli is characteristic. A variety flava has been described in Peninsular Malaysia which differs by entirely cream or yellow flowers, but as some populations consist of a mixture of white, cream and yellow plants the recognition of the variety does not appear justified ( Seidenfaden & Wood 1992).