A terrestrial herb with erect, terete, leafy stems up to 3 m tall, often sparsely branching above; stems dark green, covered by coarsely and densely glandular-villose leaf-bases. Leaves lanceolate to elliptic-lanceolate, acuminate, cuneate at base of lamina, 11–16 cm long, 2–3.5 cm wide, dark green, glabrous above, sparsely pilose beneath, about 8-nerved, sheathing at base; sheaths minutely puberulent. Inflorescence terminal or from axils of upper branches, up to 20 cm long, densely many-flowered; bracts chartaceous, ovate, acute or subacuminate, 1–2 cm long, 0.6 cm broad, glandular ciliate. Flowers small, produced in succession; sepals and petals light straw yellow, lip yellow, finely spotted with purple within and with two large maroon marks on the basal margin of the rim; pedicel and ovary 5–7 cm long, pubescent. Dorsal sepal elliptic, acute, 2–3 cm long, 1.8 cm broad. Synsepal elliptic-ovate, bidentate at apex, 2–2.5 cm long, 1.6 cm broad. Petals obliquely linear-lanceolate, acute, up to 2.5 cm long, 0.4 cm broad. Lip calceolate, broadly elliptic in outline, up to 3 x 2.5 cm; inflexed basal margins rounded. Column 0.7 cm long; staminode stalked, rhombic, acute, up to 0.5 cm long, longer than the triangular, papillate stigma. Fruits triangular-cylindrical, slightly arcuate, up to 5 cm long, round in cross-section.