– Astrophytum (2008)

By Eric Driskill (May 2008)

The genus Astrophytum is in the family Cactaceae and has four species. Its name is derived from the Greek “aster,” star, and “phyton,” plant. With the geometric shapes and patterns displayed by the various species, this is a very popular genus.

Unique to Astrophytum is the presence of small white flecks or flocking, which patterns and sometimes covers various species and cultivars. Perhaps this flocking aids water collection or protection from the sun. Regardless of its purpose, there is no doubt that it greatly adds to the popularity of the genus. Astrophytums have a geographical range from northern Mexico to southern Texas. Plants flower in summer over a period of several weeks.

One of the most popular astrophytums is A. asterias, also known as the sand dollar cactus, sea urchin cactus or star cactus. Historically, A. asterias ranged through Cameron, Hidalgo and Starr Counties in south Texas and the border states of Nuevo Leon and Tamaulipas in Mexico. Presently, this species is known from one population each in Starr County and Tamaulipas. It is listed as endangered in the U.S. Endangered Species Act and is included in Appendix I of CITES.

Fortunately, it is readily propagated by seed, and its rarity in the wild ensures that most plants encountered in nurseries are seed-grown. Plants are typically small, often 2 to 6 inches in diameter and usually 1 to 2 inches tall. Plants in habitat are very flat, barely rising above ground level. The cacti are gray-green, with numerous tufts of trichomes with very low ribs, flattened above and separated by sharp furrows.

The popularity of this species among growers and enthusiasts has ensured that a number of spectacular cultivars are available. One of the most popular cultivars is the Super Kabuto, a highly flocked white clone. For some spectacular examples of other cultivars, search any one of several Japanese or Thai nurseries.

Astrophytum capricorne has a fairly wide distribution in the Chihuahuan Desert in northern Mexico. Plants can reach 4 to 10 inches tall and 4 to 6 inches in diameter. They are green with a heavy coating of tufts of white trichomes and five to 10 brownish-black, twisted, flattened and somewhat flexible spines 1 to 3 inches long.

Astrophytum myriostigma, otherwise known as the bishop’s cap, is cylindrical, 4 to 10 inches tall and 4 to 8 inches in diameter. Typically, there are five prominent, broadly triangular ribs. A. myriostigma is found in northern and central Mexico, primarily in the Chihuahuan Desert. A. myriostigma is variable in form. Numerous varieties, subspecies and forms have been described, but conservatives do not recognize them taxonomically.

The dark-green Astrophytum ornatum, which sometimes uses the alias monk’s hood, is 12 to 40 inches tall and 6 to 12 inches in diameter, with scattered white tufts of trichomes. There is one central spine and five to 10 stout yellow radial spines that become brown with age. A. ornatum is found in central Mexico in Queretaro and Hidalgo.

One other astrophytum worthy of mention is A. myriostigma monstrose cv. Lotusland. This cultivar is almost always seen as a graft, but since offsets often produce roots, they can be rooted as well.

Most astrophytums require strong light and a light watering hand. Plants should do well in normal cactus potting mix, although some growers add limestone to remind them of the limestone formations in Mexico where the plants grow. Astrophytums enjoy a pH of 7, but you don’t have to get that precise to grow them nicely. I would suggest growing them hard to keep them compact.

No cacti collection should be without at least one astrophytum. Due to its status, you can help the genus by only purchasing plants from a nursery that you know grows them from seed, or getting seed and starting them yourself. If you do grow them from seed, you stand a chance of finding a seedling with unique flocking not offered through any nursery.