Epithelantha bokei is a species of cactus known by the common names pingpong ball cactus and button-cactus. Description Epithelantha bokei is a small, disc-shaped or cylindrical cactus that usually measures 2 to 5 centimeters in width. It is typically unbranched, with a flat or slightly concave top. Most of the plant remains below ground, with only a few centimeters visible above the surface. During dry periods, it contracts into the soil for protection. The stems are thickly covered in dense, pale-colored spines, giving the plant a white or yellowish appearance. The spines are short, with the longest reaching about 7 mm. Each areole can bear up to 90 spines, which lie flat against the stem and form dense clusters. The plant almost always grows solitary, with small, smooth, glossy stems. When dried out or losing turgor, sunken rings may appear on the surface. Young plants look very similar to mature ones, making early identification challenging. The flowers are delicate, pale pink to silvery white, protruding above the spines at the stem apex. They measure 1 to 1.7 cm long and wide, with 13 to 21 translucent inner tepals marked by pink, pinkish-tan, or greenish-yellow lines, and 8 to 13 outer tepals with scalloped edges. The flowers contain 20 to 40 stamens and white stigma lobes. They bloom mainly in late spring and early summer, opening on warm days for one or two days. The fruits are cylindrical, red, and about 1 cm long, although they may stay green if environmental conditions are unfavorable. They are bare, measuring 0.8 to 1.3 cm long and 1.5 to 4.3 mm thick. Seeds are black, glossy, and 1 to 1.4 mm long, shaped like a comma or helmet with a deep cavity near the hilum. Fruits develop in late summer and fall.Epithelantha bokei. Center for Plant Conservation.
Epithelantha bokei is often confused with Epithelantha micromeris, but it is more common in areas where both occur. The two species are distinguishable in the field, even from a distance. Epithelantha bokei is a small, ground-hugging cactus with a flat-topped, disc or cylindrical form, densely covered in pale spines, with delicate pink or silvery white flowers, and red fruits. It contracts into the soil during dry conditions and can be recognized by its dense, pale spines and flat-topped stems.
Distribution The species' native range extends from Texas in the United States to northeastern Mexico, specifically within the states of Coahuila and Chihuahua in desert or dry scrubland environments at elevations between 700 and 1,500 meters above sea level.Epithelantha bokei. Flora of North America. The species is a soil specialist, often forming dense clusters on specific calcareous substrates. It is commonly found on elevated limestone hills, mountain summits, and rocky ledges within xerophytic scrublands. Additionally, the species can occur on plains, where it grows on soils composed of gravel mixed with organic-rich earth resulting from leaf decomposition. These conditions provide localized nutrients and enable the species to thrive in extremely dry environments. Plants are found growing along with Coryphantha difficilis, Ariocarpus fissuratus, Echinocereus pectinatus, Sclerocactus scheeri, Mammillaria heyderi. Threats to the species include poaching and habitat degradation. It is in cultivation at the Desert Botanical Garden in Phoenix, Arizona.
Taxonomy Epithelantha bokei was first described by the American botanist Lyman David Benson and published in the scientific journal Cactus and Succulent Journal, volume 41, page 185, in 1969. The specific epithet honors Norman H. Boke, plant anatomist and student of the Cactaceae.Powell, A.M., Weedin, J.F. 2005. Cacti of the Trans-Pecos and Adjacent Areas. Texas Tech University Press
References
External links
USDA Plants Profile