ORCHIDACEAE
Risleya King & Pantl., Ann. Roy. Bot. Gard. (Calcutta) 8: 246 (1898).
By: Bhakta B. Raskoti
Taxon Description
Holomycotrophic herbs. Rhizome subterranean, creeping, with spaced roots. Stem erect, cylindric, leafless, glabrous, with 2 or 3 sheaths at base. Inflorescence terminal, racemose, glabrous, densely many flowered; floral bracts persistent. Flowers, widely opening, not resupinate. Sepals similar, spreading, free. Petals usually shorter and narrower than sepals. Lip adnate to base of column, superior, entire, concave, ovate, apiculate. Column clavate; anther subterminal, 2-locular; pollinia 4, in 2 pairs, waxy, caudicle absent, directly attached to a viscidium; viscidium oblong thick; rostellum stout, exserted, protruding beyond.
Taxon Statistics
Worldwide one species, distributed in Assam-Burma, E Himalaya, E Asia.
1. Risleya atropurpurea King & Pantl., Ann. Roy. Bot. Gard. (Calcutta) 8: 247 (1898).
Plants 15–17 cm tall. Rhizome narrowly conic to cylindric, 2–6 cm. Stem ridged, 7–13 cm, with 2 or 3 sheaths at base; sheaths tubular, amplexicaul, 1.5–2.5 cm, apex obtuse. Inflorescence cylindric, rachis 5–9 cm, densely up to 75-flowered. Floral bracts triangular-lanceolate, 0.5–1 × 0.5 mm, membranous. Flowers dark purple, widely opening, ca. 1–2 mm across. Pedicel and ovary 1–2 mm; ovary twisted. Dorsal sepal spreading, suboblong, ca. 1–1.5 × 0.4–0.6 mm, apex obtuse. Lateral sepals similar to dorsal sepal. Petals spreading, suboblong-lanceolate, ca. 1 × 0.3–0.4 mm, apex acute. Lip adnate to column at base, broadly ovate, concave, ca. 1–2 × 1–1.5 mm, basal margin denticulate, apexmucronate. Column ca. 0.3–0.5 mm. Capsule ovoid to ellipsoid, 3–4 × 2–2.5 mm.
Distribution: Nepal, Assam-Burma, E Himalaya, and E Asia.
Altitudinal range: 3400 m.
Ecology: Forest thickets.
Flowering: June–August. Fruiting: July–October.