How to identify and how it grows
This cactus grows in dense clumps six inches to two feet or more across, with the heads close together. They are shortened, globose or cylindrical, one to two inches in diameter, and as high. The plants are almost hidden by the dense growth of reddish brown or almost black spines. There are from fifteen to thirty radially placed spines and three to seven stouter central thorns, all of which have yellowish bulbous bases, with red-brown or almost black tips. The flowers are about an inch and a half long and as wide. The petals and sepals are narrow and lance-shaped, and from tan-purple to rose or rose-purple. The fruit is oval and light green. This cactus grows in the prairie lands and on foothill slopes, and needs a little modern irrigation.
How to grow
This Pincushion is not injured by temperatures of twenty to twenty-five degrees below zero and hence is well suited for growing in cactus gardens throughout the country. It thrives also in the warm Southwest. Young plants grow readily from seed in pots or flats, in sandy or loamy soil, with enough irrigation to keep the soil moist; part shade is desirable. Large plants prefer sandy or loamy soil, especially limestone soil with irrigation about once a month, and some shade.
California Pincushion (Mammillaria tetrancistera)
(Named tetrancistera in allusion to the four central spines)
How to identify and how it grows
The California Pincushion grows from single stems a foot high and two and one-half inches in diameter, or several in a cluster. Sometimes the stems are branched and cylindrical with a loose flabby texture. The root is narrow, conical, and fleshy. The tubercles are usually less than a half-inch long and loosely set in eight spiral rows. There are from forty to sixty-five radial spines placed in two whorls, slender and white with red-brown tips; also one to four central spines which are strongly hooked, dark reddish brown or blackish. The flowers are usually about two inches long and are purplish. The sepals and petals are ciliate and covered with many fine hairs.
How to grow
This pincushion is not injured by temperatures fifteen or twenty degrees below freezing and hence grows indoors or out; it thrives in hot, sunny conservatories or greenhouses. The plants grow easily from seed sown in sandy soil with partial shade, the soil moist but not wet. Plants may be transplanted at any season in sandy, stony, or gravelly soil, and watered once in two or three weeks during dry spells.