ORCHIDACEAE
Thunia Rchb. f., Bot. Zeitung (Berlin) 10: 764 (1852).
By: Lokesh R. Shakya
Taxon Description
Plants sympodial, epiphytic or terrestrial, lacking pseudobulbs. Rhizome short, thick. Stems close together, rather fleshy, recurved at the tip, bearing many leaves, sheathed below. Leaves distichous, sessile, lanceolate, evenly spaced along the stem, thin textured. Inflorescence a terminal, raceme, arching, many-flowered. Fertile bracts persistent, spathelike. Flowers short-lived, large, showy. Sepals and petals subsimilar, free. Lip adnate to the base of column, shortly spurred, side lobes short, embracing the column, fringed on front margin, disc with lamellae. Column slender, semi-terete at apex, 2-winged, rostellum lobed, stigma concave, pollinia 4, waxy, in two groups.
Taxon Statistics
Worldwide about 5 species, distributed in India, Bhutan, China and SE Asia. One species with two varieties in Nepal.
Thunia alba (Lindl.) Rchb. f., Bot. Zeitung (Berlin) 10: 764 (1852).
Phaius albus Lindl. in Wallich, Pl. Asiat. Rat. 2: 85, t. 198 (1831).
Key to Species
1a Lip with yellow patch, veins light yellow………………………………… T. alba var. alba
b Lip without a yellow patch, veins purple…………………………….T. alba var. bracteata
Thunia alba var. alba
Plants 30–80cm tall. Stem stout, leafy, basal portion covered by sheaths. Leaves elliptic-lanceolate to oblong-lanceolate, 10–27 X 1.8-3.5 cm, many, distichous, sessile, acuminate, membranous. Inflorescence racemes terminal, 4-8 flowered; peduncle short, sheathed; rachis 2–4 cm. Flowers sepals and petals white, lip white, with large yellow patch on base, veins yellow-orange; 8 cm across. Pedicel and ovary ca. 1.5–2 cm. Fertile bract, 4–6 cm, oblong, boat-shaped. Sepals subequal; narrowly oblong-ovate, 4–5 X 1 cm, acute. Petals oblong, ca. 4.5–6 X 0.8–0.8cm. Lip ca. 4.5–5 cm, simple, broadly oblong-pandurate, spurred; basal half convolute into a tube; apical half hooded, margins dentate-undulate; disc with 5-9 dentate-fimbriate ridges. Column ca. 3 cm.
Distribution: Nepal, W Himalaya, E Himalaya, Assam-Burma.
Altitudinal range: 600–1300 m.
Ecology: Open rocky wet slope, epiphytic on Quercus lanogenosa.
Flowering: May to June
Thunia alba var. bracteata (Roxb.) N. Pearce & P.J. Cribb, Edinburgh J. Bot. 58(1): (2001).
Limodorum bracteatum Roxb., Fl. Ind. 3: 466. (1832).
It differ from var. alba in having prominent purple veins and lacking yellow colouration.
Distribution: Nepal, W Himalaya, E Himalaya, Assam-Burma.
Altitudinal range: 600–1200 m.
Ecology: Epiphytic on tree trunk in the forest.
Flowering: May — June