Polystachya transvaalensis grows an erect inflorescence that becomes 6 cm long and bears from 5 to 12 flowers. It rarely branches. Small pointed bracts are present below each flower on the stem. Flower colour is yellowish green, tinged brown or purplish brown, more so on the outside surfaces.

The median sepal at the bottom of the flower becomes about 12 mm long, appearing as a shallow chin. The lateral sepals spread downwards, flanking the flower centre protectively like some medieval headgear or basset hound ears. Their surfaces are fleshy, glistening inside from large surface cells.

The creamy white lip over the column of this non-resupinate flower sometimes has faint purple markings, not seen on the plant in the photo. The three-lobed lip has an acutely upward pointing tip and a multitude of papillae or thin, fleshy protuberances on its lower surface. 

Flowering happens from midspring to midsummer (Pooley, 1998; www.orchidspecies.com).