It forms a small, globose-flattened solitary stem. Unlike the standard species which reaches 7–8 cm across, the gracilis variety stays ultra-compact, topping out at roughly 6 cm in diameter.
The plant typically features about 10 distinct ribs. These ribs are often nearly hidden beneath a remarkably dense, protective covering of spines.
From the cephalium, it sends out funnel-shaped, fragrant white flowers. These blooms open specifically in the late evening/night and last for only a single night.
