Calanthe odora Griff.

Kurzweil, Hubert, 2010, A precursory study of the Calanthe group (Orchidaceae) in Thailand, Adansonia (3) 32 (1), pp. 57-107 : 83-84

17. Calanthe odora Griff.

Notulae ad Plantas Asiaticas 3: 365 (1851); Hooker, Flora of British India 5: 853 (1890); Pearce & Cribb, Flora of Bhutan 3 (3): 288 (2002); Seidenfaden & Pedersen, Opera Botanica 22: 529 (2002); Chen et al., Flora of China, vol. 25: 301 (2009). — Alismorkis odora (Griff.) Kuntze, Revisio Generum Plantarum 2: 650 (1891). — Type: India, Upper Assam, Suddyah , 10.IV.1836, Griffith 477 (holo-,?K) .

Calanthe angusta Lindl. , Folia Orchidacea 6: 7 (1854); Hooker, Flora of British India 5: 849 (1890); Seidenfaden, Botanisk Tidsskrift 67: 106 (1972); Seidenfaden, Dansk Botanisk Arkiv 29: 12 (1975); Seidenfaden, Opera Botanica 114: 94 (1992). — Alismorkis angusta (Lindl.) Kuntze, Revisio Generum Plantarum 2: 650 (1891). — Type: India, Khasia, Lobb s.n. (holo-, K!).

MATERIAL EXAMINED. — Northern, Chiang Mai, Mae Sanam , 27.VI.1978, Phengklai et al. 4134 ( BKF) . — Northern, Chiang Mai, Omkoi , 14.V.1977, Santisuk 958 ( BKF) . — Northern, Chiang Mai, Ob Luang , 11.VI.1968, v. Beusekom & Phengklai 1145 ( AAU, BKF, C, K, L). — North-Eastern, Phetchabun, Nam Nao, Pollawatn s.n. ( BCU spirit 008944).— Eastern, Chaiyaphum, Phu Kiew Wildlife Sanctuary, 2.V.1997, Pooma 1527 ( BKF) . — Eastern, Chaiyaphum, Tunkamang , 29.V.1994, Geesink et al. 7056 ( BKF, K, C). — South-Eastern, Trat, Khao Kuap, 23.V.[year not given], Put 2983 (C) .

ILLUSTRATIONS. — Seidenfaden, Botanisk Tidsskrift 67: fig. 26a, b (1972) [as Calanthe angusta Lindl. ]; Seidenfaden, Dansk Botanisk Arkiv 29: fig. 2a, b (1975) [as C. angusta Lindl. ].

DESCRIPTION

Terrestrial herbs, evergreen, 12-50(-62) cm tall. Basal sheaths 1 or 2, 1.5-7 cm long. Pseudobulbs inconspicuous and largely enclosed by the leaves, up to 2.5 cm long, close together, several-noded. Leaves 3-5, perennial, elliptic-oblong, acute, 13-25 × 1.5-4.2 cm, upper surface glabrous, lower surface hairy or subglabrous; with obscure grooved petioles to 5 cm long. Infl orescences erect, arising from the base of the previous year’s leafless pseudobulb, pubescent; peduncles 26-35 cm long; sterile bracts 3-6, scattered along the flowering stem and a few clustered at its base, the lower erect or suberect and the upper spreading, the lower sheathing, broadly ovate-lanceolate, obtuse, 0.9-2.8 cm long, subglabrous or sparsely pubescent, with rather pronounced veins; raceme semi-dense or dense, 6- to many-flowered; rachis 2-9 cm long; floral bracts persistent, broadly ovate, acute, acuminate, 8-15 × 3-6 mm, shorter than the pedicel plus the ovary, sparsely pubescent or glabrous, with pronounced veins. Flowers 12-20 mm across, white with a yellow centre or with yellow spots on the lip; sweetly scented. Ovary indistinguishable from the pedicel, 13-15(-21) mm long, pubescent. Sepals broadly ovate-elliptic, obtuse or subacute, 3- or 5-veined, sometimes slightly pubescent on the outside; median sepal 7.5-12 × 5-7.7 mm; lateral sepals similar but slightly narrower. Petals oblong, obtuse or truncate, slightly mucronate, 3- to 5-veined, 7.5-12 × 3.1-5 mm, sometimes puberulous at the base. Lip (8-) 11-15 mm long, 3-lobed and the midlobe further divided into two elongate and spreading lobules, base completely united with the gynostemium, spurred, sometimes hairy at the base but glabrous above; midlobe bipartite, sinus acute, each lobule oblong, 3.8-6.2 × 2.2-3.6 mm; side lobes oblong, obtuse, 3.8-6 × 1.6-3.5 mm, spreading and pointing forwards; basal callus a semi-circular cluster of warty lumps; spur cylindric, (8-) 10-12 mm long, subglabrous to sparsely hairy.Gynostemium 3-4 mm long, sparsely hairy. Fruits not seen.

DISTRIBUTION AND PHENOLOGY

In Thailand known from a few scattered records made in the northern and eastern parts of the country. Generally widespread on the Asian continent from NE India to Indochina and S China. Found in swampy spots in open pine and dipterocarp forest and also in marshy grassland on loamy soil, from 850 to 1100 m. Flowering in May and June.

REMARKS

Calanthe odora is very similar to C. triplicata and has been treated within its synonymy ( Seidenfaden 1975), but differs clearly in the shorter spur. Furthermore, the inflorescences of C. odora appear from an old wilted shoot, as opposed to C. triplicata where the inflorescence arises from a fresh leafy shoot ( Seidenfaden & Pedersen 2002). Also the usually sweetly scented flowers of C. odora are a distinguishing feature from C. triplicata with its normally odourless flowers ( Pearce & Cribb 2002: 289). In Thailand C. odora is found in marshy grassland and swampy soil in open forest, while C. triplicata occurs usually in shaded forest habitats.