Overview
Peyotillo (Pelecyphora aselliformis), also known as the woodlouse cactus or hatchet cactus, is one of the most distinctive and highly prized botanical gems of the Chihuahuan Desert. Native strictly to limestone outcrops in central Mexico, this diminutive geophytic cactus is instantly recognized by its bizarre flattened tubercles that mimic miniature woodlice or trilobites, providing camouflage against fractured gravel soils.
Biology and Physical Characteristics
Pelecyphora aselliformis forms a low, hemispherical stem that grows flush with the surrounding limestone soil, anchored by a massive fleshy taproot. Its tubercles are laterally compressed into hatchet-like blades, topped by elongated areoles covered in tiny, pectinate spines that interlock like overlapping scales. In spring and early summer, mature crowns produce vivid magenta to carmine-violet flowers with bright yellow stamens.
Behavior and Ecology
To withstand extreme seasonal droughts and intense solar radiation, the peyotillo relies on Crassulacean Acid Metabolism (CAM), opening stomata only at night to capture carbon dioxide. During dry periods, its contractible taproot pulls the stem downward beneath the limestone scree, shielding vital tissues from scorching sun and foraging desert herbivores. Bees and small solitary wasps pollinate its crown blooms.
Conservation and Human Impact
The IUCN classifies Pelecyphora aselliformis as Endangered. Because of its unique morphology and extremely slow wild growth rate (taking decades to reach flowering size), wild populations have suffered extensive illegal extraction for commercial succulent collector markets. Habitat fragmentation from limestone quarrying and goat overgrazing further degrades its restricted native range, driving strict CITES Appendix I protections.
Interesting Factoid
The scientific name ‘aselliformis’ means ‘woodlouse-shaped,’ referring to how the interlocking rows of flattened white spines on top of each tubercle make the plant look like a colony of tiny armored pillbugs resting on rock.
Last updated: October 2026