Calanthe sieboldopsis

Description. Plants 35 - 45 cm tall. Rhizome elongate, thick. Pseudobulbs small, inconspicuous, obscured by the bases of the leaves, with 3 - 5 basal sheaths. Leaves 4 - 7, well developed and spreading at anthesis, not deciduous; blade broadly elliptic, 14 - 28 x 6.5 - 9.0 cm, apex acute; petiole-like base 9.5 - 16 cm long, usually forming a pseudostem, 8.5 - 10 cm long, 1.0 - 1.5 cm in diam. Scape arising from leaf axil, 30 - 45 cm tall, sparsely puberulent; rachis 15 - 25 cm long, laxly 8 - 11 - flowered; floral bracts persistent, lanceolate, 5.0 - 8.5 mm long, puberulent, apex acuminate. Flowers bright yellow, large, slightly fleshy, glabrous except for lip base; pedicel and ovary 18 - 20 mm long, minutely puberulent. Dorsal sepal elliptic, 15 - 20 x 5.0 - 6.5 mm, apex acute; lateral sepals narrowly oblong, 12 - 15 x 4 - 6 mm, apex acute. Petals obovate-lanceolate, 15 - 17 x 4.5 - 5.5 mm, base narrowed, apex acute; lip adnate to entire length of column wings, spreading horizontally, yellow, mottled red at base, deeply 3 - lobed; lateral lobes oblong-elliptic or falcate-obovate, oblique, 6.5 - 8.0 x 4.5 - 5.5 mm, apex obtuse-rounded; mid-lobe nearly rectangular, 6.0 - 8.5 x 4.5 - 5.5 mm, apex emarginate; disc with 3 ridges, extending to middle of mid-lobe; the proximal ends of the lateral 2 ridges enlarged, with light reddish spots and minute white hairs; spur curved, cylindrical, 12 - 14 mm, inside puberulent. Column 5.0 - 6.0 mm, thick, wings decurrent and connecting to ridges on disc; rostellum 2 - lobed; anther cap beaked; pollinia 8, clavate, equal in size, grouped into two clusters, each with a short caudicle, 0.5 mm long, attached to an elliptic viscidium.