Plants grow outside in twenty degrees of frost, but with colder weather than this they must be protected or grown in warm conservatories. They grow easily from seed in the usual way in pots with part shade and with occasional watering to keep the soil moist. They may be transplanted at any season in sandy or gravelly clay, and given enough water to moisten the soil well once in two or three weeks during dry months. Snowball Pincushion (_Mammillaria Oliviæ_) (Named _Oliviæ_ in honor of Mrs. C. R. Orcutt, who shared her husband’s interest in these plants) How to identify and how it grows The Snowball Pincushion is covered with a dense coat of white spines, looking much like a snowball lying on the ground. It grows on solitary stems or in some instances in clumps, is globose, and has twenty-five to thirty-five thorns. The plant is covered with radially placed spines about half an inch long, translucent white and somewhat twisted. There are four centrals in the spine groups. The flowers of this plant resemble those of the Sunset Cactus, and are pink and pink-rose with the margins fringed in white. They are very showy and about an inch long. The pink flowers contrast well with the glistening white spines, making this cactus one of the handsomest of its kind, growing on the deserts and foothills of southern Arizona. How to grow The same care and treatment is suggested as for the Sunset Cactus. Green Flowered Pincushion (_Mammillaria viridiflora_) (Named from its green flowers, which are very uncommon among cacti) How to identify and how it grows The Green Flowered Pincushion Cactus grows from single stems or in small clusters and is cylindrical or globose. The stems are two to four inches long and as much as three inches in diameter. This plant, also, has a flabby texture, with the tubercles arranged in eight to twelve spiral rows, which are disposed rather loosely. The radial spines, slender and needlelike and wide-spreading, loosely interlocking with those of the other spine clusters, are white with brown tips. The central spines are hooked and slender, longer and stouter than the radials, about two inches in length, brown and brown-red. The flowers are not at all showy and are less than an inch long and wide; the sepals and petals are green. The fruit is ovoid and less than an inch long, with a dull purplish or green-purple color. How to grow Plants will endure outdoor temperatures of twenty or twenty-five degrees below freezing. In colder climates they will thrive in warm, sunny conservatories. Plants grow readily from seed in sandy loam with occasional watering and part shade. Transplant older plants in gravelly clay with enough water to keep the soil moist. Watering once in two weeks during droughty spells is sufficient. This cactus is very attractive as a potted plant, and outside should be given some shade. Showy Pincushion Cactus (_Coryphantha aggregata_)