Calanthe hirsuta Seidenf.

Kurzweil, Hubert, 2010, A precursory study of the Calanthe group (Orchidaceae) in Thailand, Adansonia (3) 32 (1), pp. 57-107 : 66-68

3. Calanthe hirsuta Seidenf.

Dansk Botanisk Arkiv 29: 39 (1975) . — Type: Thailand, Nakhon Ratchasima Province, Ban Tha Chang , 24.XII.1930, Put 3497 (?holo-, BK; iso-, B!, C!, K!, P!). Calanthe sp. , 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); based

on Put 3497.

ADDITIONAL MATERIAL EXAMINED. — Eastern, Chaiyaphum, Sukhakul sub Seidenfaden & Smitinand 9578 (C spirit); 9594 (C spirit). — Central , Nakhon Nayok, Khao Yai ,? Buakhlai 122 ( BCU spirit); 24.I.1965, Seidenfaden & Smitinand 5846 (C spirit). — Unspecified, Khao Yai, Cumberlege 903 (K spirit) .

ILLUSTRATIONS. — Seidenfaden & Smitinand, The Orchids of Thailand – A Preliminary List, part III: fig. 255a-d (1961) [as Calanthe sp. Put 3497]; Seidenfaden, Dansk Botanisk Arkiv 29: fig. 13a-c (1975).

DESCRIPTION

Terrestrial herbs, deciduous, (38-) 67-83 cm tall. Basal sheaths not seen. Pseudobulbs prominent, ovoid, conical, c. 5 × 3 cm, close together, covered by greyish-silvery leaf sheaths, glabrous, with a constriction below the apex. Leaves not present at the flowering time, not seen. Inflorescences arising from the basal part of the pseudobulb, erect at the base and nodding in the apical part, softly pubescent;peduncles 35-55 cm long; sterile bracts 5-9, erect or suberect, scattered along the flowering stem and a few clustered at its base, lanceolate-oblong, acuminate, 1-5 cm long, pubescent, the lower sheathing, occasionally decayed at the flowering time; raceme semi-dense, 4- to many-flowered; rachis (7-) 15-22 cm long; floral bracts persistent, ovate-lanceolate, acuminate, (28-)30-40 × 3-10 mm, densely pubescent. Flowers to 30 mm across, light rosa and lip with darker dots; sepals and petals with recurved apices. Ovary indistinguishable from the pedicel, 26-40 mm long, pubescent.Sepals ovate-lanceolate,aristate-acuminate, 4- to 5-veined,(14-)16-21 ×(5.5-) 6-7mm, pubescent on the outside. Petals ovate-elliptic, obtuse, acuminate, 3- or 5-veined, 13.5-18 × 5-7.7 mm, glabrous. Lip 3-lobed, 15-20 × 16-20 mm, base not united with the gynostemium, spurred, glabrous; midlobe rounded or oblong, slightly emarginate, 4-13 × 3.5- 4(-12) mm; side lobes flabellate, obtuse, 2.5-10 × 5-7(-12) mm, much broadening towards the apex; callus consisting of one fat, very obscure keel at the base; spur cylindric, (25-) 27-35 mm long, pubescent. Gynostemium 4-6 mm long, with a column-foot up to 3 mm long. Fruits not seen.

DISTRIBUTION AND PHENOLOGY

Very rare in the Eastern and Central regions, currently considered as endemic to Thailand. The habitat is

not known, collections come from 1300 to 2000 m. Flowering between December and January.

REMARKS

This species is very similar to Calanthe cardioglossa ( Seidenfaden 1975) but differs by having much longer floral bracts. Further differentiating characters are the spur which is mostly more than 27 mm long and the lip which is apically emarginate and lacks the prominent keels found in C. cardioglossa . Originally this species was thought to belong into the affinity of C. rubens ( Seidenfaden & Smitinand 1961) .

Two collections of this species from Chaiyaphum (Sukhakul sub Seidenfaden & Smitinand 9578 and 9594) agree with the type specimen in their structure but differ in their somewhat larger size .