Epithelantha micromeris (Button Cactus)

Scientific Name

Epithelantha micromeris (Engelm.) F.A.C.Weber ex Britton & Rose

Common Names

Button Cactus, Ping-pong Ball Cactus

Synonyms

Mammillaria micromeris (basionym), Epithelantha micromeris subsp. micromeris, Epithelantha micromeris var. micromeris, Epithelantha petri

Scientific Classification

Family: Cactaceae
Subfamily: Cactoideae
Tribe: Cacteae
Subtribe: Cactinae
Genus: Epithelantha

Description

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.

Photo via flickr.com

Hardiness

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.

Origin

Epithelantha micromeris occurs in the United States in Arizona, New Mexico and Texas, and in Mexico in the states of Chihuahua, Coahuila, Durango, Nuevo León, San Luis Potosí and Zacatecas.