Peristylus spiralis

Terrestrial, leafy herbs with small, oblong, pyriform or globose tubers and fleshy root fibres; stem with spike 15-45 cm long, slender, flexuous with many, lanceolate sheaths above the leaves. Leaves 2.5-6.2 cm long, linear-lanceolate, obtuse, acute or acuminate, upper leaves merging into the sheaths on the stem, 5-7 veined, bases sheathing. Flowers greenish-white, secund, variable in size, in slender, lax-flowered, spirally twisted spikes, 5-25 cm in long; floral bracts 6-8 mm long, lanceolate, lower bracts longer than the ovary. Sepals and petals subequal, 2.5-3 mm long, obtuse, 1-veined. Dorsal sepal oblong or liner-oblong, concave; lateral sepals linear, falcate, reflexed. Petals ovate or linear-oblong. Lip variable, longer than the sepals, cuneate, 3-cleft to about the middle, lobes variable short, obtuse, median usually shorter, broader and strongly recurved; spur a minute globose sac; column short, continuous with the lip, rostellum trifid, stigmatic processes clavate. Anther lateral, 2-loculed, loculi parallel, tubes absent; pollinia 2, pyriform; caudicles short; glands oblong.

References:

The Plant List  India Biodiversity Portal  JSTOR | Global Plants: Type of Peristylus spiralis A. Rich. [family …  IOSPE Photos