Tephrocactus (2016)

By Eric Driskill (January 2016)

Tephrocactus is a small genus of cacti in the subfamily Opuntioideae, formerly placed within the large genus Opuntia. The decision to pull it from Opuntia resulted from studies done by several people, including Robert Wallace.

Tephrocactus was described by Charles Lemaire in 1868, the same year he raised Coryphantha to generic level. The name tephrocactus is derived from the Greek “tephra,” ashes, referring to the dull, ash-colored stems of some species.

Tephrocactus are endemic to Argentina. The plants do have glochids, which are distinctly sunken into the areoles. Spines range in length from short to very long, and can be needlelike, daggerlike, papery or absent. The stems grow in distinct branching segments.

Unlike the flat pads of most opuntias, tephrocactus segments are round – resembling cylinders, egg-shaped and spherical. Many species grow their segments in a slightly zigzag stack, although some species grow in vertical rows.

The segments of most species are quite fragile and break off very easily. Since broken-off segments readily root, this is likely one of the major factors in distribution. It is certainly the leading culprit in why people have multiple plants of the same species in their collections and often find themselves being generous with a starter plant for another hobbyist.

Some species of this genus are very popular and common in cultivation. Those species are popular most likely for the bizarre appearance of their segments or spines, moreso than for their flowers. The flowers of most Tephrocactus species are either white or pink, and sometimes yellow, and one species has red blooms.

The flowers are quite nice, but do not usually appear on many species until a plant is more than a couple segments tall. Since the plants grow rather slowly, it takes a lot of patience and luck not to knock a segment or two off accidentally.

The next time you see a large specimen in a show, take time to appreciate the patience and risk of the grower who brought it. Just transporting many of these plants is hard to do without breaking off segments.

The genus has six species. You could represent the entire genus with half a dozen plants. On the other hand, you could fill entire benches with plants without having two that look identical.

Most of the species have a wide range of growth characteristics, which is evident with a quick Internet search. Determining which characteristic you want represented through variety in your collection might help narrow down which species to pursue.

T. alexanderi comes in a wide range of segment size and density of spines, and has blooms that are white, pink or red. T. articulates has plants that differ in both segment size and spines, from small to absent, with other plants exhibiting distinctively papery spines. T. geometricus is known for its segments, which can appear perfectly spherical with various spine lengths and numbers.

Consider adding a tephrocactus to your collection … right after you find a spot on the bench far enough back to minimize the risk of brushing it and knocking off segments.