Copiapoa hypogaea

Copiapoa hypogaea

Root: Tuberous-napiform, connected though a narrow region to the main stem.
Stem: Grey-brown or more commonly bronzed, depressed-globose, 3-4 cm in diameter (up to 7 cm in cultivation), the aerial part is almost disc-shaped and almost sunken in the ground with white wool in the centre, also in the older areoles. Epidermis smooth or roughened.
Ribs: 10-14(16) divided in extremely low often spiralled tubercles up to 4-8 mm apart, about 4-7 mm in diameter and up to 5 mm tall.
Areoles: Small 1-3 mm wide, sunken, oval, with white felt and well separated.
Spines: Completely absent on older part of the plant.