Pale green orchid is an erect forb, 3-7dm tall with leafy stems and an inflorescence that is a congested spike with elongate bracts. Flowers are sessile, greenish-yellow or green, 5-6mm wide. Its lip is deflexed, 4-6mm, often irregular on the margin, bearing a conspicuous, fin-like extension on the upper side just below the middle, and usually with a small lateral lobe on each side at the base. Spur is 3-6mm. Its fruit are glabrous, erect capsules that are more or less sessile and taper on both ends. Its leaves are cauline. The lower leaves are well developed, lance-linear to lanceolate or lance-elliptic, to 20cm long and 5cm wide. The upper leaves are much reduced or bract-like.
It can be distinguished from other orchids by its lip, which has an erect tubercule on the upper side, below the middle, its leafy stem, and its congested spike with elongate bracts.