As a rule, in writing columns for this Journal, I have tried to focus on plants which are reasonably easy to grow in cultivation; but in my humble opinion, the various species of Ariocarpus do not qualify as easy plants. Many of the members of the Central Ohio Cactus Society (myself included) admit that they have killed a plant or two from this genus. But the various species are amongst the most unusual and attractive of all cacti, with low stems (in some species, growing nearly flush with the surface of the ground, with odd triangular tubercles barely protruding above the ground’s surface). All species are compact, growing to (at most) several inches in height, and to about 10 across or perhaps slightly larger in the largest species (most of the species tend to remain much smaller). While most plants tend to remain solitary, mature plants may eventually produce a few offsets, and a few exceptional clones may even produce compact clusters of a dozen or so stems. The tubercles vary considerably between the species, and for that matter, often show considerable variation within a species: these may be flat, convex or concave, smooth, or intricately rough, long and narrow or short and squat depending upon the species, variety or clone. Except for their earliest months of growth (and in some plants of A. agavoides), no mature plants will produce spines. Some plants of Ariocarpus retusus and A. scapharostrus, may not even produce areoles, which is usually considered one of the fundamental diagnostic traits of the Cactus Family. But let there be no confusion, these ARE cacti, despite their many distinctly un-
Very old, and well grown plants are hardly to be forgotten, as these are unique and very attractive plants; possibly best described as living cubist sculptures. Oftentimes, the greater portion of these plants grow below the surface of the soil, with large tuberous roots which may be carrot-
Because these plants produce such very large tuberous roots, all species of this genus tend to be very sensitive to excess water, and may have a tendency to rot in cultivation unless provided a potting medium with very sharp drainage. Plants also need very bright light to produce good growth, and also seem to prefer warm temperatures (from the upper 80's to mid 90's and possibly warmer) during their growing season, so plants are best grown in a bright greenhouse, or should be moved outdoors onto benches in direct sunlight (after plants have been sufficiently acclimated to the increased light) during the warm months from late spring through early autumn. Provided with excellent drainage, these plants will tolerate frequent thunderstorms (although it may be wise to erect screens over these plants to protect them from hail). Exposed to summer sun, high summer temperatures and rain, my plants have rewarded me with growth, and the occasional flower. Plants perpetually maintained inside the home, will probably suffer from a lack of light and temperatures which are too cool to produce any significant growth. These plants, if they produce any growth at all will grow considerably slower than plants moved outdoors or grown in a greenhouse.
The various species of Ariocarpus have a well deserved reputation of being slow growers. Several years ago, I ordered a few plants from Mesa Garden, and these included data on when they had been planted -
The species of Ariocarpus can be quite a challenge to grow well, especially without the benefit of a greenhouse or Florida-
I cannot pretend to be an expert with these plants: I have managed to maintain several for a number of years, and several plants have managed to produce a flower or two each year for the last few years, but on the other hand, I have also killed several plants over the years, and since I have treated all of my plants more or less identically, I can only surmise that the plants which continue to grow and flower under my care have done so in spite of my treatment, rather than because of it. I provide my plants with a potting medium with a bit of extra grit worked into it to provide a particularly free-
The plants which I have had the greatest success are:
Ariocarpus agavoides: a miniature species growing to about 3 inches across, but usually remaining much smaller. This species produces very long and narrow tubercles, these growing to about 1½ in length and to about ¼ inch wide. Plants usually only produce a relatively few tubercles, and in my plants, these are practically deciduous, lasting perhaps 2 years before drying, and being replaced with newer growth. Flowers are usually large for the size of this plant, opening to as much as 1½ inches. Flowers are deep pink to magenta in color, and petals tend to be acute, terminating in a point. This species is also unique in that some plants may occasionally produce an odd spine on its areoles. These spines are quite short, and generally grow appressed against the tubercle.
Ariocarpus fissuratus: plants usually grow to no more than 6 inches in diameter (and are usually smaller). Plants are usually very low, with broad triangular tubercles with very rough upper surfaces. Flowers are pale to deep pink, opening to about 1.5 inches across. This is the only species known to occur in the United States, with several populations identified from part of the lower Rio Grande Valley in Texas; otherwise, all other populations of this species and the remaining species of this genus are endemic to Mexico.
Ariocarpus kotschoubeyanus is another very small species, growing up to about 3 inches in diameter, but are usually much smaller, reaching flowering size at slightly more than ½ inch in diameter. Plants are flat-
Ariocarpus retusus. This is perhaps the largest growing species, growing to as much as 10 inches in diameter. Its stems are gray-