Pterygodium cooperi flowers are white, flushed pink when ageing under pale green to purplish green hoods. The shallow hood is comprised of the green dorsal sepal, elliptic in shape and the two white, asymmetrical lateral petals.
Some dark speckling may occur on the inside of the petals. The lip is fused at its base to the column and has a white appendage that curves back into the flower centre. In the flower’s column the rostellum arms diverge. Flower diameter is about 8 mm (Pooley, 1998; www.eurekalert.org; www.africanorchids.dk).