Gymnocalycium AMERHAUSERI - Amerhauser's chin cactus, Gymnocalycium amerhauseri.
Gymnocalycium is a genus of plants in the family Cactaceae, comprising about 70 species widely distributed in South America, especially in Argentina, Brazil, Paraguay, Uruguay, and Bolivia at elevations of 800-3,000 m (2,600-9,800 ft) above sea level, on granitic and clay soils.
Gymnocalyciums are valued for the graceful outlines of their stems, usually globular and flattened, with a diameter of 4 to 15 cm (1.6 to 6 in), while their height is roughly half the diameter. The base color of the stem 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 can only develop in a grafted state. The stems are generally distinctly ribbed, with tubercles located on the ribs. The spines are moderately rigid, often recurved.
The plants are valued for their spectacular flowering. The flowers are funnel-shaped with a short tube, forming from areoles at the top of the stem and opening during the day. The flower tubes in representatives 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. The fruits are oblong, juicy or dry, containing large black seeds with a texture characteristic of the genus.
Amerhauser's chin cactus is a small cactus with a solitary flattened stem, a characteristic dark green epidermis color, and short appressed spines resembling small spiders. The plant is a geophyte; its stem barely rises above the soil surface. The stem is usually solitary, flattened-globular to spherical, thick, glossy, dark green, bluish-green, or grayish-green in color, up to 2.5 cm (1 in) high and 5-6 cm (2-2.4 in) in diameter.
The ribs are tuberculate, usually 8 in number. Areoles are oval, initially covered with yellowish-white wool, becoming bare with age. There are 5-6 radial spines; they are straight, slightly recurved, radiating star-like, 6-12 mm (0.24-0.47 in) long, white with a darker brownish-red base. The central spine is initially absent and appears only on mature plants, measuring 1.2-1.4 cm (0.47-0.55 in) in length.
Funnel-shaped flowers up to 3 cm (1.2 in) in diameter appear from June until autumn near the apex. They are colored from cream-white to pale pink, with a reddish throat. The scales on the flower tube are green with a pinkish-white margin. The plant flowers quite readily even at a young age. Flowering is fairly long-lasting. The fruits are dark green, oval to spindle-shaped, about 3.3 cm (1.3 in) long and up to 1.9 cm (0.75 in) in diameter. The seeds are spherical, 1-1.2 mm (0.04-0.05 in) in diameter.