by Bruce Brethauer
The members of the genus Stenocactus are amongst the most recognizable of cactus. Almost all of the species have unique, very narrow, sharp edged and undulating ribs. The curiously shaped ribs has earned the various species of Stenocactus the name of "Brain Cactus", although to my eye, the ribs bear a closer resemblance the pleats of a bellows on a camera or accordion, and to some styles of smocking. In either case, these pleated ribs gives these plants a very distinctive and attractive appearance. All species are native to the Chihuahuan Desert of northern and central Mexico, and all of the species tend to be smallish plants with globelike to short columnar stems. Plants typically remain solitary, but may eventually produce a few offsets in some plants. In older taxonomies, approximately 2 dozen species were recognized, and Britton and Rose suggested that further research may have resulted in the discovery of additional species in time; however, modern treatments have subsumed several species together, and most modern treatments only recognize about 10 species.
This plant is probably one of the species which has been merged in recent re-classifications; the original tag on my plant when I acquired it read "Stenocactus longispinus", but I could not find this name in any of my cactus publications, likewise, a web search did not produce any hits of plants which look anything like my plant. One site illustrated several plants identified as "Stenocactus crispatus longispinus", with several photographs of plants which bear a passing resemblance to the seedling illustrated here, so I am using that name here for now, although this could be in error. One of the traits of this variety is that it has unusually long, and flattened central spines which project upwards from each areole; this trait is especially apparent in the photograph taken about 6 or 7 years ago of a plant featured in the cactus show of the Midwest Cactus and Succulent Society. It is possible that this plant may be the parent of the plant which I am growing today. While these flattened spines have the appearance of those of Tephrocactus papyracanthus, or the paperlike spines of Leuchtenbergia principis, the spines of this plant are quite rigid, and end in a very sharp point. so this plant should be treated with respect when moving or repotting. In addition to the protection offered by these spines, the flattened centrals may also function as a sort of camouflage, helping the plant to blend in when it grows amongst desert grasses. This plant also has remarkably attractive flowers, with vivid purplish magenta mid-veins, fading to palest pink at the petal margins. The flowers are rather smallish, measuring to nearly 3/4 of an inch, and do not open widely. These are produced in clusters on the apex of the plant; it is one of the first cacti in my collection to flower in spring - often producing its flower buds while the plant is still being maintained in its cold and dry winter dormancy condition.
Stenocactus crispatus longispinus has proven to be an easy plant for me, and responds well to my general recommendations for growing cacti and other succulents. I have discovered that this plant is tolerant of very low temperatures, and has survived several degrees of frost on several occasions (twice when it was in flower - and on both occasions, neither the plant nor the flowers suffered any apparent ill effects). It seems to benefit from extra cool conditions during its winter dormancy - with temperatures down to the low 40's - or even cooler. For the last two years, I have wintered my plant on the windowsill of a picture window, which I weather sealed with plastic sheeting to prevent drafts in the winter (with the plant sandwiched between the glass and the plastic sheeting). This space cooled significantly at night - in some instances the window panes would frost over, but on sunny days, this space would warm from solar heating, possibly to as much as 80 degrees or warmer - I did not water this plant at all from November through April. When I removed this plant from this space at the end of April this year, it was in bud, and was in full bloom within two weeks.
These plants really benefit from full sun, and should be moved outdoors as soon as temperatures permit (don't worry about light to moderate frosts - most species can easily tolerate these). but if the plant has been wintered in the dark interior of your home, gradually acclimatize it to increasing exposure to daylight - grown outdoors through the warmer months of spring and summer, it will show impressive growth. Because of its tolerance to cold, plants can be left outdoors until the first fall frosts.
The stems of this species have a tendency to become corky with age, a trait which is even evident on my 3 year old "seedling": I'm not sure if this is an actual trait of this plant, of if it is evidence that they will benefit from being watered with acidified water.
There was a time when plants of Stenocactus used to be more readily available: they were frequently available in mixed selections of cacti and other succulents, but are practically never to be found at most "big box" nurseries today. These are readily available from a number of mail order nurseries including Mesa Garden (under this genus' older name of Echinofossulocactus), Miles To Go, and Bob Smoley's Gardenworld, and may occasionally be found at regional Cactus Society shows and sales (I got mine from a sale of the Midwest Cactus and Succulent Society) . the Stenocactus are so easy to grow, tolerant of extended drought, and are so easy to flower, that they deserve a place in more collections. Should you ever manage to find a plant at your local nursery - give it a try.