Ariocarpus kotschoubeyanus aka Living Rock

Ariocarpus kotschoubeyanus is a small cactus. It comes from the northeast of Mexico. It belongs to the cactus family, Cactaceae. Its English names include living rock and star rock. Its range starts in central Coahuila and runs south to Querétaro. It also grows in Nuevo León and San Luis Potosí. Other states in its range are Tamaulipas and Zacatecas. Many small groups grow apart across this broad range. It grows in and near the Chihuahuan Desert. Kew lists its habitats as desert and dry shrubland.

This cactus forms a low rosette, shaped like a star. Most plants rise just a few centimetres above the soil. Much of the plant lies below the ground. A large taproot stores water below the small, visible stem. This swollen root has a shape much like a turnip. Plants tend to grow alone, though some form clumps. Old areoles may produce side shoots, but this is rare. The stem has a flat top and a sunken centre.

Dark olive-green growths called tubercles form the plant's visible face. These growths pack together and spread out across the soil surface. Each tubercle has a shape much like a triangle. It has a sharp tip and no spines. It is longer than it is wide. A groove filled with wool runs along its upper face. The groove runs toward the tip. These grooves mark the areoles on the tubercles. The low shape and muted colour help hide the plant. On bare ground, it can look much like dry mud. Its pinkish flowers make it easier to find among the soil.

Wild plants grow on plains and hills in silt rich in gypsum. This soil comes from limestone in the land around them. Their sites can get quite wet during summer rains. Some places flood from time to time in that season. In harsh drought, the parts above ground can shrink. Mould may cover them while the taproot stays alive. These wild conditions do not set a watering plan for pots. The supplied sources for this species give no firm garden hardiness range.

Human actions threaten some groups of wild plants. Settlements and waste dumps affect the sites where they grow. People who collect them illegally have cut numbers at some sites. Local people also gather plants for use as medicine. That use does not prove that they help or are safe. The evidence supports no food use and gives no toxicity assessment.