Callostylis Blume, Bijdr.: 340 (1825).
By: Devendra M. Bajracharya
Taxon Description
Epiphytic herbs. Rhizome well developed, stout, creeping, covered by sheaths. Stems well spaced on a stout rhizome, or tufted, short to elongate, pseudobulbous, thick, somewhat clavate and consisting of only a many internodes. Leaves 2–5, distichous, arising from nodes at apex of pseudobulb, suberect, conduplicate, leathery, coriaceous, glabrous, dorsiventrally flattened. Inflorescences axillary racemes, short, with many flowers opening in succession, erect or spreading, axis covered by short, dense, stellate hairs, peduncle pubescent. Floral bracts reflexed, suborbicular or broadly ovate both surfaces shortly tomentose. Flowers resupinate, usually cream-colored to orange-yellow, often with a dark brown lip, pedicel and ovary tomentose. Sepals sub-similar, spreading, entire, fleshy, grayish-white tomentose dorsally, sparsely white-pubescent ventrally, mentum absent. Petals free, oblong, smaller than sepals, narrow. Lip small, pentagonal shape, mobile, entire, bearing a large shiny callus at centre, articulate to column foot, closely pressed to column and column foot, often expanding at base. Column curving, long, foot at right angles to column, often somewhat sigmoid, shorter or longer than column; pollinia 8, obliquely shortly clavate. Capsules oblanceolate-oblong.
Taxon Statistics
Worldwide three species, distributed in S. China to tropical Asia, China, Himalayan region, India, and SE Asia. One species in Nepal.
1. Callostylis rigida Blume, Bijdr.: 340 (1825).
E. rigida (Blume) Rchb. f.; Eria discolor Lindl., Tylostylis discolor (Lindl.) Hook. f.
Plants epiphytic, 25–35 cm tall. Rhizome creeping, with internodes and cylindric sheaths. Pseudobulbs shiny, oblong-fusiform or narrowly fusiform, 6–16 × 2–3 cm, distally 4-or 5-leaved. Leaves blade glossy, sub-oblong or narrowly elliptic, 12–17 × 2.4–4.3 cm, obtuse to subacute, leathery, base contracted into a short petiole, apex unequally bilobed. Inflorescence racemes 2-6, axillary or extra-axillary, up to 13 cm long, softly yellowish-brown, downy-pubescent; peduncles at base with 2-5 imbricate, tubular sheaths, with many distant sheaths above; sheaths 0.5–1.5 cm apart, 0.2–1.0 cm long, tubular, clasping, softly pubescent; rachis laxly 10–20-flowered. Floral bracts reflexed, suborbicular or broadly ovate, 3–4 mm, both surfaces shortly tomentose. Flowers up to 1 cm long, 1.2 – 1.7 cm across, greenish-yellow, dull white tomentose externally, lip dark-brown to dark purple. Pedicel and ovary 2.5–7 mm. Sepals sub-similar, spreading, 0.8–1.1 x 0.4 — 0.5 mm, elliptic-oblong, entire, obtuse, fleshy, grayish-white tomentose dorsally, sparsely white-pubescent ventrally, mentum inconspicuous or completely absent. Petals narrowly elliptic-obovate, 7–8 × 3.5–4 mm, obtuse. Lip entire, movably joined to the column-foot with a short claw, broadly cordate to ovate, 4–6 x 3–5.5 mm, apiculate to mucronate, apical margins up-turned, upper surface sparsely pubescent, disk with a shining, quadrate, cushion-like callus. Column ca 4 mm long, curved forward at right angle. Capsules 3 — 5 cm long, oblanceolate-oblong.
Distribution: E. Himalaya, Nepal and SE Asia.
Altitudinal range: 450–1700 m.
Ecology: Epiphytic on tree trunks in tropical and sub-tropical forests and lithophytic boulders on mountain slopes.
Flowering and fruiting: May–June.