Calanthe succedanea Gagnep.

Kurzweil, Hubert, 2010, A precursory study of the Calanthe group (Orchidaceae) in Thailand, Adansonia (3) 32 (1), pp. 57-107 : 68-69

4. Calanthe succedanea Gagnep.

Bulletin du Muséum national d’Histoire naturelle, sér. 2, 3: 324 (1931); Seidenfaden & Smitinand, The Orchids of Thailand – A Preliminary List, part III: 339 (1961); Seidenfaden, Dansk Botanisk Arkiv 29: 32 (1975); Seidenfaden, Opera Botanica 114: 89 (1992). — Types: Laos, Bassac, Thorel 2629 “ 2623 ” (syn-, P!); Cambodia, Popokwil , Kampot, I. 1904, Geoffray 354 (syn-, P!) .

ADDITIONAL MATERIAL EXAMINED. — Northern, Mae Hong Son, Huay Hei, Triboun 281 (l) ( BK spirit). — Northern , Chiang Mai, Doi Suthep , Watthana 2157 ( QBG spirit). — Northern , Phitsanulok, Khao Soi Dao , Shimizu et al. 23873 (C spirit). — North-Eastern , Phetchabun, Thung Salaeng Luang , 29.XII.1982, Koyama et al. 31927 ( BKF); 30.XII.1975, Seidenfaden & Smitinand 5606 (C spirit). — North-Eastern, Loei, Phu Krading, 14.XI.1979, Shimizu et al. 22676 ( BKF, C spirit); 23076 (C spirit); 23216 (C spirit). — Eastern, Chaiyaphum, Phu Khieo, XI.[year not given], without collector 39 ( BKF spirit). — South-Eastern, Chanthaburi, Khao Soi Dao, Chatchai s.n. ( BCU spirit 008945); 13.XI.1969, v. Beusekom & Smitinand 2191 ( AAU, BKF, C, E, L). —? Without locality, Suratabandu s.n. (K spirit) .

ILLUSTRATIONS. — Seidenfaden, Dansk Botanisk Arkiv 29: fig. 11a, b (1975).

DESCRIPTION

Terrestrial or lithophytic herbs, once recorded as an epiphyte (Triboun 281 (l) ), deciduous, 30-47 cm

tall. Basal sheaths not seen. Pseudobulbs prominent, ovoid, conical, 2.5-11.5 × 2-3 cm, close together, covered by greyish-silvery leaf sheaths, glabrous. Leaves 4, apparently short-lived, usually present at the flowering time, lanceolate-oblong, acute, 16-49 × 3.8-11.8 cm, almost always glabrous; petioles 3-7 cm long. Inflorescences arising from the base of the pseudobulb, erect, softly pubescent; peduncles 18-35 cm long; sterile bracts 3-6, erect or suberect, scattered along the flowering stem and a few clustered at its base, lanceolate-oblong, acuminate, 1.3-3.6 cm long, pubescent, sheathing; raceme lax, up to 11-flowered; rachis 12-14 cm long; floral bracts persistent, ovate-lanceolate, longacuminate, (12-)15-19 × 3-6 mm, shorter than the pedicel plus the ovary, pubescent. Flowers to 21 mm across, pink, lip dark purplish flecked inside; flowers turning orange-red or yellow when older. Ovary indistinguishable from the pedicel, 20-35 mm long, pubescent. Sepals ovate-lanceolate, aristate-acuminate, pubescent on the outside; median sepal 3- to 5-veined, 9-13.8 × 4.5-5.6 mm; lateral sepals 3- to 4-veined, 10-14 × 4.5-6 mm. Petals obovate-elliptic, obtuse or subacute, 3-veined, 8-13 × 3.3-6 mm. Lip 3-lobed, 11-14 × 16-20 mm, base not united with the gynostemium, spurred; midlobe broadly rounded, 4-8 × 4-9 mm; side lobes spreading, oblong, obtuse, 4-8.3 × 4-9.5 mm, much broadening towards the tip, wavy-edged; callus consisting of three fleshy keels in the basal third of the lip, median keel continuing onto the epichile as a high thin lamella; spur cylindric, 15-29 mm long, pubescent. Gynostemium 3-4 mm long, straight, stout, with a c. 3 mm long column-foot. Fruits not seen.

DISTRIBUTION AND PHENOLOGY

In Thailand, Calanthe succedanea is only known in the northern and eastern parts of the country. It has also been recorded in Indochina.The species is found in dry evergreen forest from about 550-1200 m. Flowering in November and December.

REMARKS

Calanthe succedanea and C. cardioglossa are very similar and share the 3-lobed lip with wavy-edged truncate side lobes which are much broadening towards the apex as well as the gynostemium which is not united with the lip base. In C. succedanea the median keel of the hypochile continues onto the epichile as a high thin lamella while in C. cardioglossa it continues onto the epichile merely as a low rounded keel or strong vein. Intermediates in this respect were not found in the present study, and consequently both are recognized as separate species. Previously the two taxa were referred to as possibly conspecific by Seidenfaden & Smitinand (1961) but were later recognized as separate species by Seidenfaden (1975).

The high thin lamella of the lip midlobe is very short in the collection Koyama et al. 31927.