This genus forms a remarkable group of spherical, which may be recognized from the more or less distinct “chin” or chin-shaped extension below the areoles. The spines are spreading, and sometimes recurved, suggesting in certain species a kind of spider. This is noticeable, especially on G. denudatum, which is sometimes nicknamed the “spider ”.
Gymnocalyciiim denudatum. S. Brazil, Uruguay, and Argentina. This plant has 5 to 8 very broad ribs, only slightly notched, with the chin below the areoles hardly pronounced. Spines number 5 to 8; there are: no central spines. Theare green, margined with white, the inner petals white or pink with a. green band.
Gymnocalycium saglione. N. Argentina. The dull: greenare globular, with 10 to 13 ribs according to the age of the plant. While young, the areoles; are felty and at first have erect spines which later-bend outwards. Radial spines number 7 to 12,, centrals 3. The flower has a short tube, greeni outside, white or pale pink inside. This plant is fre-quently found in collections, and is but requires half shade. Argentina. The are globular, glaucous green, possessing 12 to 14 ribs. The chins below the areoles are prominent. Radial spines number about 7; there are no centrals. Flowers greyish-green, white inside. This is a beautiful species, and very free flowering.