The genus Ariocarpus [ar-ree-oh-KAR-pus] is made up of eight different species of perennial cactus belonging to the family Cactaceae.
All are native to Mexico and Texas, where they grow in soil rich in limestone content. They also grow well like Pleiospilos on a windowsill.
You may hear members of this genus commonly referred to as:
- Living Rocks of Mexico
- Living Rock Cactus
- Peyote Cimarron
- Flowering Rocks
- Seven Stars
- False Peyote
- Living Rock
- Star Rock
By any name, the species within this genus are so similar as to be nearly indistinguishable from one another.
Size & Growth
These cacti are quite small, growing to a diameter of about 6″ inches and the height barely rising above the ground’s surface.
Flowering Rocks grow from large, turnip shaped roots. The foliage consists of rock-like, firm, rugged tubercles.
In the center of each plant, you’ll find a tuft of woolly hair from which the flowers emerge.
The tubercles grow in a rosette formation and tend to become yellow with age.
Tubercles vary in shape depending upon the species of Ariocarpus.
Some are quite flat, while others have a protruding appearance.
Flowering & Fragrance
Most people grow Living Rocks for their interesting foliage, but the rare flowers are certainly stunning and breathtaking.
Mature, healthy plants produce large, funnel-shaped flowers atop interesting, woolly structures.
Flowers appear in midsummer and measure 1″ or 2″ inches across.
Depending upon the species, flowers may be white, yellow, purple, pink, or magenta.
They transition into black, pear-shaped seeds late in the summer.
Light & Temperature
Grow Seven Stars in an area providing consistent, bright, indirect sunlight.
When grown as houseplants, these cacti do well at a comfortable room temperature.
Grown outdoors, they are winter hardy in USDA hardiness zones 9 through 11.
Because they are so low growing, they can tolerate temperatures as low as 25° degrees Fahrenheit (-4° C).
Watering & Feeding
- Throughout the growing season, allow the soil to dry out thoroughly and then drench it thoroughly.
- After the plant has finished blooming and gone to seed late in the summer, withhold water until springtime.
- Water is stored in the root throughout the winter months.
- The quality of water and the method of watering are quite important.
- It’s best to use rainwater or purified water, especially in areas where the tap water contains many chemicals.
- Avoid overhead watering.
- It’s best to use bottom watering, but don’t allow the plants to sit in water for longer than half an hour.
- If you begin to notice the salts are crystallizing on the surface of the soil around your plants, do a very thorough top watering to wash the excess salts through the soil.
- Fertilize early in the spring and mid-summer with a one-quarter strength water-soluble solution with high phosphate and potash content.
- Ariocarpus does need soluble calcium and an array of minerals.
- Still, you must be careful not to use calcium hydroxide (i.e., hydrated or horticultural lime) because it is very damaging to the plant’s roots.
- Instead, use dolomitic limestone, which delivers both magnesium and calcium as soluble bicarbonates.
Soil & Transplanting
Use a well-draining cactus soil mix and avoid any mix containing peat as it is damaging to the plant’s root structure.
If you wish, mix up the potting medium similar to the soil where these plants naturally grow.
It should be about half coarse sand, 30% heavy clay loam, and 20% limestone chippings.
Use pumice to make up part of the sand, and include a bit of slow-release, high potash granular fertilizer.
To accommodate the plant’s bulbous roots, it’s a good idea to use a rather flexible plastic pot with plenty of drainage holes in the bottom.
The roots can swell and grow as they store water, and this can result in the breakage of terra-cotta pots.
A shallow, broad pot is usually preferred; however, if your plant already has a long taproot, you’ll need to select a pot to accommodate it.
Repot every couple of years by simply moving up to the next larger size pot.
Wait until the soil is dry around the root before you repot.
Be sure to shake off all of the old soil and replace it completely.
Grooming & Maintenance
These slow-growing plants require no regular grooming.
Just tend to the light, temperature, and water needs consistently, and the plants will maintain their good looks effortlessly.
How To Propagate Ariocarpus Cactus
Because all members of this genus are threatened or endangered, you may have no choice but to grow from seed.
Follow standard cactus germination protocol by sowing the seed on the surface of a tray of a cactus mix.
Cover it lightly with a bit of sand and mist frequently to keep the sand evenly moist.
Never collect cuttings or root segments of this plant in the wild.
If you can take cuttings from plants, or those of another collector, rock cactus will grow from cuttings or bare root.
Either way, keep the soil evenly moist.
When you observe new growth, begin treating the plant as a mature plant.
Ariocarpus Pest or Disease Problems
When kept as a houseplant, Living Rock is susceptible to all of the same pests usually plaguing cactus.
Watch out for mealybugs, scale insects, and the like.
It is best to prevent pest invasion by delivering a precautionary dose of systemic insecticide in the first watering of the springtime and again late in the summer.
As plants age, they become more susceptible to diseases and weakening of the root system.
When this happens, a plant may die suddenly.
Help your plants enjoy the longest life possible by extending the period between repotting to three years and by withholding water a bit more often.
Stronger sunlight also seems to help.
Is The Living Rock Plant Toxic Or Poisonous?
Living Rock contains toxic and bitter alkaloids which protect it from being eaten by herbivorous animals.
Is The Living Rock Invasive?
These slow-growing plants cannot be considered invasive.
In fact, in the wild, their status is threatened or endangered.
This is because they have become greatly in demand by collectors, and they are not able to replace themselves quickly enough to survive.
All species within the genus are considered threatened, and three species are formally listed as endangered.
- A. agavoides
- A. bravoanus
- A. scapharostrus
These plants are protected by the Mexican government, the United States government, and the Convention on International Trade in Endangered Species of Wild Fauna and Flora (CITES).
Suggested Ariocarpus Uses
Unless you happen to live in this plant’s native range or in an area which replicates its ideal circumstances, Ariocarpus can only be kept as a container plant in the home or greenhouse with forays outdoors during the warmer months.
In a conducive climate with the right soil conditions, living rock is an interesting and intriguing addition to your rock garden, but you must be sure the soil underneath the rocks is loose and free draining.
Traditionally, living rock cactus has several folk medicine uses.
It is considered a power plant (delivering healing powers).
Because of this, it is used in both ceremonial and medicinal contexts among indigenous people.
The plant also has many potential pharmaceutical uses.
It contains small amounts of phenylethylamine alkaloids, such as hordenine, which has some antibacterial qualities and also appears to be an effective activator of norepinephrine.
Hordenine has effects on the sympathetic nervous system, which include an increase in blood pressure and heart rate.
It may also have some value as a vasoconstrictor.
Contrary to popular belief, Living Rock does not contain mescaline.
And it is worth knowing the cactus which does contain mescaline also contain greater amounts of hordenine than does Living Rock.