The Turk’s Cap or Melon Cactus is a very variable species.
The spherical to shortly cylindric, dark green stems are up to 20 cm high.
There are up to 15 ribs with areoles having white woolly hairs.
The yellowish to dark brown spines are up to 6 cm long but are variable.
There can be up to 15 straight or curved radial spines and 0 to 4 central ones.
The cephalium is usually small but can be up to 15 cm high.
The areoles have white hairs and reddish-brown bristles.
The red to pink flowers are only 1.5 mm across with a 5 mm long tube.
The pear-shaped red fruit are under 2 cm long.