Growth Habits: The plant has globose stems, more or less flattened at the apex. The bodies often clumping to form a compact mound. Individual bodies are usually up to 1 inch in diameter (2.5 cm), occasionally more; it has small tubercles, 1 mm long; small areoles, slightly woolly at the juvenile stage; 20 or more white spines, about 2 mm long, sometimes longer at the apex of the plant.
Scientific name: Epithelantha micromeris
Common names: The Button Cactus.
Synonyms: Epithelantha rufispina, Epithelantha micromeris var. rufispina, Epithelantha micromeris var. densispina, Mammillaria micromeris, Cactus micromeris, Epithelantha densispina,
Etymology: The generic name Epithelantha derives from the Greek word epi meaning “upon, on, at, over”; the Greek word thele meaning “nipple” referring to the tubercles, and anthos meaning “flower”. (The genus name implies: “flowers upon the tubercles”). Micromeris: The name literally means made up of tiny parts.
Origin: USA (Arizona: Santa Cruz and Cochise County, New Mexico, western Texas), Mexico (northern Chihuahua).
Light: My own plant seems to prefer light shade, where it gives of its best, but most cactus literature states that it is equally happy in full sun as well.
Compost: The compost needs to be even more free-draining than normal as this plant has a tap root which tends to rot if the compost remains wet for too long a period.
Water: Water in moderation, allowing the compost to dry out totally between waterings. This will not harm the plant in any way.
Flower: The flower is quite small, pink in the throat shading to almost white at the outer limit of the petals. The anthers are pale yellow. It almost looks to be made of icing sugar.
Fruit: These are the crowning glory of the plant. A vivid, almost luminous reddish pink, with small black seeds. If left undisturbed they will last on the plant for almost the whole year.
Min. temp: 50°F (10°C). Depending on the species the plant[s] will accept almost freezing conditions for short periods without showing any signs of distress. However I have no experience of this and would not recommend it.
Cultivation: This cactus is not too difficult to maintain if the necessary precautions regarding watering and open compost are followed. If a slightly deeper pot than normal is used, this well help to accommodate the taproot (which is quite large for the size of the plant).
Habitat: In desert and grasslands from 3000 to 4500ft (1000 to 1500m) of elevation. It has quite a variable and widespread distribution.
Comments: These plants stand out well in a collection. The white spines cover the whole of the epidermis and in a well grown plant the green body is undetectable. This particular plant has a collector’s number SB125. SB standing for the well known plant collector Steve Brack. The No. 125 denotes that the original plant was found at Arteagas Canyon, Saltillo, Coahuila, Mexico.
I do have one that has clumped, but felt this one showed off the plant body to best advantage. I am sure that many of you own this plant in one form or another. There is much debate about how many species there are. Or are they all forms, subspecies or varieties of the same plant. That is down to the botanists and taxonomists, rather than the amateur enthusiast.