Calanthe clavata Lindl.

Kurzweil, Hubert, 2010, A precursory study of the Calanthe group (Orchidaceae) in Thailand, Adansonia (3) 32 (1), pp. 57-107 : 79-80

12. Calanthe clavata Lindl.

Genera and Species of Orchidaceous Plants: 251 (1833) ; Hooker, Flora of British India 5: 854 (1890); Seidenfaden & Smitinand, The Orchids of Thailand – A Preliminary List, part IV, 2: 793 (1965); Seidenfaden, Dansk Botanisk Arkiv 29: 22 (1975); Seidenfaden, Nordic Journal of Botany 6: 162 (1986); Seidenfaden, Opera Botanica 114: 99 (1992); Seidenfaden & Wood, The Orchids of Peninsular Malaysia and Singapore: 175 (1992); Pearce & Cribb, Flora of Bhutan 3 (3): 295 (2002); Chen et al., Flora of China, vol. 25: 296 (2009). — Alismorkis clavata (Lindl.) Kuntze, Revisio Generum Plantarum 2: 650 (1891). — Type: India / Bangladesh border, Sylhet, Wallich s.n., Wallich’s Catalogue 7343 (holo-, K-WALL).

MATERIAL EXAMINED. — Northern, Chiang Mai, Doi Suthep, 8.XII.1910, Kerr 210 (C spirit, K). — Northern , Chiang Mai, Doi Pui , 22.XI.1989, Maxwell 89-1434 ( CMU). — Northern, Chiang Mai, Doi Inthanon, XI.[year not given], Koorkhamthod et al. 272 ( BKF spirit). — Northern, Chiang Mai, Jawn Tong, 15.I.1993, Maxwell 93-41 ( CMU [Sc], CMU [Sc] spirit). — Peninsular, Chumphon, Thorut 19 ( BCU spirit). — Peninsular, Surat Thani, Ko Pa-ngan, 10.IV.1929, Kerr 0742 (K); 7.XI.1927, Put 1192 ( BK, C, K); 9.XI.1927, 1239 ( BK, K). — Without locality, without date, Pumicong 331 ( QBG, QBG spirit) .

ILLUSTRATIONS. — Seidenfaden, Dansk Botanisk Arkiv 29: fig. 7a-d (1975); Seidenfaden & Wood, The Orchids of Peninsular Malaysia and Singapore: fig. 75j, k (1992).

DESCRIPTION

Terrestrial herbs, evergreen, glabrous, 28-80 cm tall. Basal sheaths 1-2, 2-20 × c. 1 cm. Pseudobulbs inconspicuous, several-noded, 10-12 cm apart on a creeping rhizome, the segments with c. 7 internodes, rhizome c. 1 cm thick. Leaves 2-6, perennial, lanceolate-oblong, acute, 23-90 × 3.4-9.5 cm; with grooved petioles 13-20 cm long. Inflorescences erect, arising on the rhizome next to the leafy shoot; peduncles to 30 cm long; sterile bracts 4-8, scattered along the flowering stem and a few clustered at its base, erect or suberect, inflated, tubular, lanceolateoblong, acute, 2.8-6 cm long, sometimes falling off early; raceme cylindric, dense or semi-dense, many-flowered; rachis 10.5-22 cm long; floral bracts caducous, narrowly lanceolate, long-acuminate, 30-50 × 3-8 mm. Flowers to 20 mm across, yellow, operculum whitish. Ovary 7-8.8 mm long, with a pronounced distinction from the 8-12 mm long pedicel.Sepals ovate-elliptic, acuminate or apiculate, 5- to 7-veined; median sepal 9-14 × 4-6.7 mm; lateral sepals 10-15 × 4-7 mm. Petals obovate-elliptic to somewhat spathulate, acute, 5- to 7-veined, 9-14 × 4-6.5 mm. Lip 3-lobed, 8-13.5 mm long, spurred; midlobe rounded rectangular, apically emarginate, 3-5 × 3-4.3 mm, sometimes with a small tooth in the sinus; side lobes round, 2-3 × 2-3 mm, with two short lamellate keels between them; spur clavate, 8-10 mm long, somewhat curved, apically sometimes slightly bifid. Gynostemium 5.6-7 mm long, united with the lip in the lower two thirds and the upper part free. Fruits ellipsoid, 10-13 × 5-6 mm.

DISTRIBUTION AND PHENOLOGY

In Thailand only recorded in the North and the Peninsula. Generally widespread from the eastern Himalayas to Indochina and China and southwards

to Peninsular Malaysia. Found in evergreen and deciduous forest with pine, on damp ground by stream, from about 700 to 1400 m. Recorded over granite. Flowering mainly in November and December, and occasionally in January and April.

REMARKS

Calanthe clavata and the following species C. densiflora are very similar with their fairly dense inflorescences which arise directly from the rhizome next to the leafy stem, and also their flower structure lacks obvious differences.The two species have been considered as conspecific in the past (e.g., King & Pantling 1898), but were maintained as two separate species by Seidenfaden (1975, 1992) and Pearce & Cribb (2002) which is also followed here. However, the latter authors point out that “further fieldwork is needed to resolve the difficulty”.

Calanthe clavata differs in its laxer and longer inflorescence (rachis 10.5-22 cm long; as opposed to 1-3[-5] cm long in C. densiflora ) and longer peduncle (to 30 cm long; as opposed to 9-18 cm long in C. densiflora ). Also the flowers of C. clavata are normally smaller, with sepals measuring 9-15 mm (mostly 14-16 mm long in C. densiflora ), and also have a shorter gynostemium (5.6-7 mm in C. clavata ; as opposed to mostly 12-13 mm in C. densiflora ). Another difference is the spur which is clavate in C. clavata , but cylindric to weakly clavate in C. densiflora .

An interesting feature of the two species is the gynostemium which is united with the lip only in its basal one to two thirds and the upper gynostemiumportion is free. In Calanthe clavata the collection Thorut 19 is unusual as the fusion of the lip to the gynostemium is fairly extensive with only the top part of the gynostemium free.