Epithelantha micromeris (Engelm.) F.A.C.Weber ex Britton & Rose
Button Cactus, Ping-pong Ball Cactus
Mammillaria micromeris (basionym), Epithelantha micromeris subsp. micromeris, Epithelantha micromeris var. micromeris, Epithelantha petri
Epithelantha micromeris is a small cactus, up to 2 inches (5 cm) tall and up to 1.6 inches (4 cm) in diameter, characterized by its white-grey spines growing on a globular shaped stem. The density of its white spines give it the illusion of being completely grey, making it very difficult to see the green color beneath. It produces small, pink-white flowers, often considered to be some of the smallest of the cacti. These flowers give way to a bright red, cylindrical fruit which contains several black seeds and also is edible.
USDA hardiness zones 8b to 11b: from 15 °F (−9.4 °C) to 50 °F (+10 °C).
How to Grow and Care
To encourage better flowering, allow the plants to enjoy a cooling period in the winter and suspend watering. Unlike many other cacti, which use their ribs as storage devices, Mammillaria feature raised tubercles, from which spines emerge. When you water, the tubercles will expand to allow for increased water storage. The flowers emerge from the axils of these tubercles on the previous year's growth, which accounts for their interesting halo effect. It's imperative that the cactus is not exposed to prolonged dampness and sitting water. Never let your cactus sit in a dish of water. Lastly, make sure to fertilize during the growing season for the best results.
Repot as needed, preferably during the warm season. To repot Mammillaria, make sure the soil is dry before repotting, then gently remove the pot. Knock away the old soil from the roots, making sure to remove any rotted or dead roots in the process. Treat any cuts with a fungicide. Place the plant in its new pot and backfill with potting soil, spreading the roots out as you repot. Leave the plant dry for a week or so, then begin to water lightly to reduce the risk of root rot.
Learn more at How to Grow and Care for Mammillaria.
Subspecies, Varieties, Forms, Cultivars and Hybrids
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