Gymnocalycium

Its name derives from Greek and literally means "naked calyx", in reference to the calyx of the flower, which is devoid of hairs and scales. It includes a vast number of globular cacti, consisting of stems with protruding ribs and, sometimes, transverse grooves; completing the picture with robust and often curved spines, very thick and long in some species, few and thin in others. Except for rare exceptions, they do not reach remarkable dimensions, therefore they are perfect to be cultivated in pots even in small spaces, moreover they are highly appreciated for their particular flowers