Does a Living Rock Cactus Spread?

Habitat

• Living rock cacti survive in the inhospitable Chihuahuan Desert, which is composed of limestone and gypsum hills and rockeries. The region is bone-dry for at least half the year and experiences searing heat and icy cold temperatures. The genus ranges over a large area of Mexico, but some species are found only in micro-climates. Ariocarpus retusus is the most prevalent species and has the widest range. Living rock cactus is often grown in the home interior and makes an interesting dish specimen.

Size

• Ariocarpus may get as large as 6 inches or more across but this scarcely qualifies it as a spreading plant. Some species are less than an inch at maturity. Most are about 2 inches tall and wide. The low-growing cactus is easily mistaken for a rock. Collection is difficult on those of the species that do not produce much seed as they tend to grow fairly solitary. Others grow in groups or clusters when seeding is successful, which makes them easy to see. Spread of the plant by seed is a slow process. Conditions must be just right to form seed and for germination.

Description

• This genus has very different forms. Some of the plants resemble rosettes, others spiky crowns and still others look like crystallized rocks. Most of the cactus are dark gray to green but the color varies by area and site conditions. The cactus may live for hundreds of years and grows a huge taproot. The root traditionally was used as a glue, and the Mexican name, chaute, means glue. The living rock has many medicinal uses and was part of Indian ceremonies. Living rocks do not spread from underground stems or stolens, only by seed.

Ariocarpus Retusus Spread

• In addition to being the most widespread of the living rock cacti, Ariocarpus retusus is also the largest. It may grow to 1 foot in diameter. When seeded, it tends to cluster. Often these clusters of the cactus will be several feet in width. The plant's spread is dictated by environmental conditions. Fruits retain the seed for many years. A new plant is usually started when the parent plant dies and the fruit is exposed to release the seed. A nurse plant is often needed and Selaginella is a symbiotic fern that will shelter the seedlings.