Epithelantha micromeris ssp polycephala, or Button Cactus, is a small, very cold hardy cactus native from Arizona to Texas and Northern Mexico. The cactus is usually 1-2 cm (less than 1 inch) across and may form clumps up to 4 inches (10 cm) across. The top is usually depressed and has small tubercles bearing 12-20 flattened white spines which almost give it an appearance of being woolly. This is a very challenging cactus to grow. With very good drainage they will live outside in USDA zone 6-10.
Blooming: In the greenhouse, Epithelantha micromeris ssp polycephala bloom in late winter to early spring. This species has the smallest flowers of the Cactaceae. The very small whitish-pink flowers are approximately 0.25 inches (7 mm) across. They are not particularly showy. The flowers are followed by small red fruits that resemble chili peppers.
Culture: Epithelantha micromeris ssp polycephala need full sun with a very well drained soil mixture. In the greenhouse, we use a soil mix containing coarse sand and loam, with very small gravel added to ensure good drainage. Plants need a fairly deep container to accommodate the long tap root. Plants are watered and allowed to dry thoroughly before watering again. We fertilize them only once during the growing season with a balanced fertilizer diluted to ½ the strength recommended on the label. During the winter months, plants are placed in the cold room and not given any water at all. Watering during this period can result in plant death.
Propagation: Epithelantha micromeris ssp polycephala is propagated by division of large clumps or from seed.
Epithelantha micromeris ssp polycephala was featured as Plant of the Week June 30-July 6, 2006.
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Cal's Plant of the Week was provided as a service by the University of Oklahoma Department of Microbiology & Plant Biology and specifically Cal Lemke, who used to be OU's botany greenhouse grower and an avid gardener at home as well. If the above links don't work, then try the overview site. You may also like to look at the thumbnail index. ©1998-2012 All rights reserved.