ORCHIDACEAE
Thelasis Blume, Fl. Ned. Ind.: 385 (1825).
By: Lokesh R. Shakya
Taxon Description
Plants epiphytic. Stem pseudobulbous. Leaves 1 or 2, subsessile, arising from tip of pseudobulb.
Inflorescence arising from base of pseudobulb, slender, densely many flowered. Flowers uniformly green or pale green, small, not opening widely. Sepals subsimilar. Petals lanceolate or narrowly ovate. Lip sessile on base of column, simple, entire, concave at base. Column short, without foot, pollinia 8, in 2 groups of 4, waxy.
Taxon Statistics
Worldwide about 25 species, distributed in tropical and subtropical Asia and the Pacific islands. Two species in Nepal.
Key to Species
1a Pseudobulbs conical. Leaves 16–20 cm. …………………………………..… 1. T. longifolia
b Pseudobulbs ovoid-globose, slightly flattened vertically. Leaves 3–13 cm. ….. 2. T. pygmaea
1. Thelasis longifolia Hook.f., Fl. Brit. India. 6: 87 (1890).
Plants 15–20 cm. Pseudobulbs conical, ca. 1.5 X 2 cm. Leaf 1, narrowly oblong, 16–20 X 1–2.5 cm, apex acute, fleshy. Inflorescence 16—20 cm. Peduncle 14–16 cm, slender, with a few basal sheaths. Rachis 2–4 cm. Fertile bracts broadly ovate, ca. 2.5 X 2 mm, apex acuminate, persistent. Flowers uniformly green, ca. 5 mm across, not opening widely. Pedicel and ovary ca. 1 mm. Sepals subsimilar, ovate or ovate-elliptic, 3.5–4 X 1.5–2 mm, apex obtuse. Petals narrowly-ovate, ca. 3 X 1.5 mm, apex acute. Lip entire, elliptic-ovate, ca. 4 X 1.5 mm, tapering to minutely emarginate apex. Column ca. 1.5 mm.
Distribution: Nepal, W Himalaya, E Himalaya, Assam-Burma.
Altitudinal range: 1000–1200 m.
Ecology: Epiphytic on Schima wallichii.
Flowering: August–October.
2. Thelasis pygmaea (Griff.) Lindl., J. Proc. Linn. Soc., Bot. 3: 63 (1858).
Euproboscis pygmaea Griff., Calcutta J. Nat. Hist. 5: 372 (1845).
Plants 8–13 cm. Pseudobulbs ovoid-globose, slightly flattened vertically, ca. 1 X 1–2 cm. Leaves 1 or 2, narrowly oblong, 3–13 X 0.5–1 cm, apex obtuse or acute, fleshy. Inflorescence 10–15 cm. Peduncle 5–9 cm, slender, with a few basal sheaths. Rachis 2–4 cm. Fertile bracts broadly ovate, ca. 2.5 X 2 mm, apex acuminate, persistent. Flowers uniformly pale green, 3–6 mm, not opening widely. Pedicel and ovary ca. 2.5 mm. Dorsal sepal ovate-lanceolate, ca. 3 X 1.5 mm, apex acute. Lateral sepals ovate, ca. 3.5 X 2 mm, connate at base. Petals lanceolate, ca. 3 X 1.5 mm, apex acute. Lip entire, ovate-triangular, ca. 3.5 X 2.5 mm, apex acuminate. Column 2.5 mm.
Distribution: Nepal, E Himalaya, Assam-Burma, subtropical Asia.
Altitudinal range: 1000–1500 m.
Ecology: Epiphytic on Schima wallichii.
Flowering: July–August.