Mammillaria johnstonii

Description

Mammillaria johnstonii is a species of plant in the genus Mammillaria in the cactus family (Cactaceae). The specific epithet johnstonii honors US botanist Ivan Murray Johnston. Mammillaria johnstonii usually grows solitary, occasionally sprouting from the base. The globular to short cylindrical, cloudy bluish-grey-green shoots are 15 to 20 centimeters high. The four-edged warts contain milky sap. The axillae remain bare. The 2 central spines, rarely 4 to 6, are bluish-brown, straight, one protruding, the others spreading. They grow 1 to 2.5 centimeters long. The 10 to 14 radial spines are needle-like, stiff, white with a brown tip. They are 6 to 9 millimeters long. The flowers are white to light pink or cream-colored with pink to brownish central stripes. They grow up to 2 centimeters in diameter. The scarlet fruits are spherically swollen. They contain brown seeds. Mammillaria johnstonii is found in the Bahia San Carlos in the Mexican state of Sonora. The first description as Neomammillaria johnstonii was in 1923 by Nathaniel Lord Britton and Joseph Nelson Rose. Charles Russell Orcutt placed the species in the genus Mammillaria in 1926. In the IUCN Red List of Threatened Species, the species is listed as Endangered (EN). H. listed as critically endangered.