Epithelantha is a genus of just two species of cactus, both of which are native to the southwest United States. They are considered dwarf cacti since they often reach less than 2 inches (5 cm) in height. Epithelantha has sharp white spines which can be either long or short and bright pink or white funnel shaped flowers which appear in late winter to early spring on the very top of the plants. When the flowers have finished blooming in early summer, striking bright red fruits appear in clusters on top of the cacti. This genus is often called button cacti, or pingpong-ball cacti, due to its small size.
These types of plants can be found in dry grassy or desert areas, where they usually grow in large clusters. This is due to the fact that the seeds fall to the ground and often sprout right next to the mother plant. They are occasionally carried by the wind or by animals to grow in farther reaching areas. Often these cacti will grow in crevices between rocks or in the midst of gravel or pebbles and may take root on the steepest of cliffs.
While Epithelantha can only be grown outdoors in the warmest locations, it is often kept as a houseplant. It is fairly easy to grow, but requires direct sunlight as well as a coarse potting soil and good drainage. Regular potting soil is not appropriate for cactus plants, and special mixes are available in garden centers. The room temperature should not drop below 50° Fahrenheit (10° Celsius). When watering, they should be thoroughly soaked, and then left to dry out completely before being watered again.
In winter, Epithelantha plants go dormant and can be placed in a cool, dark room until spring. During this time they usually require no watering at all. In the spring, they should be brought back into a warm, sunny room and lightly fertilized with a water soluble fertilizer made just for cacti.
Epithelantha can be started from seed in a light, sandy soil. The pots should be kept covered to keep them moist until the seeds have germinated, and they given plenty of sunlight and grown like mature cacti. These plants also produce offshoots which can be removed and potted up to form new plants. These should be kept away from sunlight and misted frequently until rooted and then moved to a sunny window.
Like many other cacti, Epithelantha is prone to insect damage. Spider mites are among the most common as are mealy bugs and scale. These can usually be eliminated with a strong spray of water or by applying an insecticidal soap.