Gymnocalycium MIHANOVICHII - Gymnocalycium mihanovichii.
Gymnocalycium is a genus of plants in the family Cactaceae, comprising about 70 species widely distributed in South America, particularly in Argentina, Brazil, Paraguay, Uruguay, and Bolivia at an altitude of 800-3000 m (2600-9800 ft) above sea level, on granite and clay soils.
Gymnocalyciums are prized for their elegant stem outlines, typically globose and flattened, with a diameter of 4 to 15 cm (1.6-6 in), with height being approximately half the diameter. The primary stem color varies from grayish-green to brownish-green, sometimes with an almost gray or almost brown tint. Some cultivars feature unusual red or yellow stems devoid of chlorophyll; such plants are capable of developing only when grafted. Stems are usually distinctly ribbed, with tubercles situated on the ribs. Spines are moderately rigid, often recurved.
The plants are valued for their showy flowering. Flowers are funnelform, with a short tube, developing from areoles at the top of the stem and opening during the day. Floral tubes in members of this genus, unlike most other cacti, lack bristles and hairs and are covered with smooth scales. Coloration varies from white and pink to red, yellow, greenish, or brownish-yellow. Fruits are oblong, juicy or dry, containing large black seeds with a texture characteristic of the genus.
Gymnocalycium mihanovichii is a plant whose natural habitat includes the river valleys of Argentina and Paraguay. This cactus has a broad, ribbed, globose reddish-brown stem up to 6 cm (2.4 in) in diameter and about 5 cm (2 in) in height. The ribs are prominent, narrow, wavy, triangular in cross-section, 'equipped' with centimeter-long (0.4 in) pale radially spreading spines. Flowers are funnelform, multi-petaled, yellowish-green or light pink, about 5 cm (2 in) in diameter.