About Ariocarpus retusus Scheidw.
Ariocarpus retusus Scheidw. produces flattened, spherical shoots that range in color from gray-green and blue-green to yellow-green. Shoots grow 3 to 25 centimeters tall and 4 to 30 centimeters in diameter. Its erect, spreading warts protrude above the soil, are crowded at the base, and have somewhat pointed or sharp tips with rounded or flat tops. The warts measure 1.5 to 4 centimeters long and 1 to 3.5 centimeters wide, and may be as long as they are wide or up to twice as long as they are wide. Areoles occasionally grow at the tips of the warts. Flowers of this species range from cream to light yellow or pinkish red, and may also be white, sometimes with a red central stripe; flowers measure 3 to 5 centimeters in diameter. Its elongated fruits are 1 to 2.5 centimeters long, and its chromosome count is 2n = 22. This species is native to Mexico, where it occurs from the states of Coahuila and Nuevo León south along both sides of the Sierra Madre Occidental to San Luis Potosí, Tamaulipas, and Zacatecas. It grows in the high Chihuahuan Desert at elevations between 1,300 and 2,000 meters, found on limestone, on rocky slopes, and in grasslands.
