Also, I need to quickly point out that the photos from the last article were taken by that maestro of a photographer, Joey de Castro. We inadvertently left out the credits the last time. Joey also took the fantastic photos shown in today’s article. Many thanks again, Joey!
I thought I would start off the year with an article on some of the most sought after cacti in the world today. These are the astrophytums, a small genus of highly attractive cacti mainly from Mexico and some parts of Texas. In particular, I wanted to focus on the highly-coveted white forms and cultivars of the genus, the fantastic hybrids derived from Astrophytum asterias and A. myriostigma cultured by the Japanese and known as "Super Kabuto" and "Onzuka." While there are many other special cultivars developed by the great Japanese horticulturists these two are by far the most popular worldwide.
"Astrophytum asterias, as it is well known, is a spineless cactus, with a perfectly geometric form resembling that of the sea urchin. The stem is globose, quite flattened and reaches a diameter of 10 cm and a height of 8 cm. It usually has eight flat ribs, separated by shallow furrows. The areoles are conspicuous, white, 3-4 mm wide, usually woolly. The color of the plant is grayish-green, and the epidermis is covered by white dots arranged sometimes along lines, sometimes according to more irregular patterns. The flowers are about 5 cm wide and 3 cm long, yellow with a reddish throat.
"The unique form known as ‘Super Kabuto’ is distinguished from the normal Astrophytum asterias by the epidermis, which does not have simple dots, but a mosaic of extensive white spots that make the plant look intensely maculate. In Japan there are many and beautiful forms of Super Kabuto, which differ for the diverse patterns of these spots. It would be difficult to mention them all: they range from completely white forms (white type) to forms with woolly spots (snow type), and forms with a maculation like the shape of fly’s wings (zebra type).
"It is well known in Japan that the original Kabuto plants originated as natural mutations in habitat. Tony Sato (1986, 1993), a leading Japanese expert on cacti and succulents, related that Masaomi Takeo found the parent plant of Super Kabuto in 1981 in a US nursery, where the plant had turned yellow from neglect. Nevertheless, its large white dots were remarkable. Under Takeo’s care, the plant re-rooted and bloomed the next year. About 30 percent of its first hundred seedlings had similar dots. Sato bought the parent plant and all the seedlings and gave them the name ‘Super Kabuto.’ He first offered them in his nursery catalog of April 1983.
"Regretfully, the original plant died, but many offspring survived. Takeo created many seedlings from crosses with A. asterias. Some of these strains showed distinctive characteristics and were called "Super Snow White" and "Zebra" (or "Tiger"). The Snow White strain had very dense dots covering the entire stem, while Zebra has bands of dots. The late A. Shimizu (1994) noted that these two strains arose from crossing with densely dotted clones of A. asterias. In the early crossings some of the parents were not true A. asterias and therefore spiny clones often appeared. Breeders of Kabuto try to obtain larger stems and areoles without any epidermal cracking, but this is very difficult to do."
In 1979 he wrote: "I bought a four-ribbed plant (‘A’) from S. Yoshinaga, a famous breeder of A. myriostigma. ‘A’ was three-ribbed when juvenile; by crossing it with another three-ribbed plant of A. myriostigma (‘B’), which later increased the number of its ribs, I obtained about a hundred seeds. Among the seedlings was one clone (‘C’) with large dots, and in 1976 I crossed C with A and also with a separate clone without large dots. Of the hundreds of seeds resulting, about five percent had large dots." This strain is called "Onzuka Rampo" after the breeder. Sato (1980) stated that there were several forms of Onzuka rampo: 1. with dense large white dots; 2. with sparse, large white dots; 3. with dots forming horizontal stripes; and 4. with fluffy dots.
Although Onzuka did not mention it, many enthusiasts point out that Onzuka rampo has genes of A. myriostigma var. tutensis in maturity as it develops columnar stems.
As can be seen from Joey’s excellent photos, these various astrophytum cultivars and hybrids are very beautiful, have their own distinct and desirable qualities, and would be prized plants in any collection. Rare is the collection that doesn’t have at least one or two astrophytums represented. But as prices come down and availability increases, more and more collections now contain not just the regular species but also a Super Kabuto and/or an Onzuka. These snow-covered succulents are truly some of the masterpieces produced in all of horticulture. And once again, we have the Japanese to thank for.