Gymnocalycium MONVILLEI 'ACHIRASENSE' - Gymnocalycium monvillei achirasense, Gymnocalycium Achirasense.
Gymnocalycium is a genus of plants in the cactus family (Cactaceae), comprising about 70 species widely distributed across South America, especially in Argentina, Brazil, Paraguay, Uruguay, and Bolivia at elevations of 800-3000 m (2625-9843 ft) above sea level, on granite and clay soils.
Gymnocalyciums are valued for the elegant outlines of their stems, usually globose and flattened, with a diameter of 4-15 cm (1.6-5.9 in), with height being roughly half of the diameter. The primary stem coloration varies from grayish-green to brownish-green, sometimes with an almost gray or almost brown tint. Some cultivars feature unusual red or yellow stems lacking chlorophyll; such plants are capable of developing only in a grafted state. The stems are typically distinctly ribbed, with tubercles situated along the ribs. The spines are moderately stiff, often recurved.
The plants are prized for their showy flowering. The flowers are funnelform, with a short tube, developing from areoles at the stem apex and opening during the day. Unlike most other cacti, flower tubes in members of this genus lack bristles and hairs and are covered with smooth scales. Coloration varies from white and pink to red, yellow, greenish, or brownish-yellow. The fruits are oblong, juicy or dry, containing large black seeds with a texture characteristic of the genus.
Gymnocalycium monvillei achirasense is a compact globose cactus with a flattened-rounded stem 6-10 cm (2.4-3.9 in) in diameter. The ribs are low, broad, weakly pronounced, separated by shallow furrows along which large, smoothed tubercles are positioned. The areoles are rounded, with grayish-white wool, bearing up to 8 radial spines of grayish-yellow or gray-brown color; central spines are usually absent. Stem coloration varies from matte green to bluish-gray.
Flowering occurs in early summer. The flowers are large, broadly funnelform, white or cream with a pinkish tint, the petals having pointed tips and a thin pink vein down the center. The floral tube is short, with delicate scales. The fruits are oval, green, containing small dark brown seeds.