Stenocactus phyllacanthus
Native range: Central Mexico (Hidalgo, Guanajuato, and San Luis Potosí)
Known names: Brain Cactus, Finger Cactus
Hardiness: USDA Zone 8 (10-20°F) to 11, protect from prolonged frost and freezing temperatures.
Mature Size: 2"-4" tall, 2"-4" wide (slow grower, typically adding 0.5"-1" per year)
Light: Half day direct sun, full sun
Water: Allow soil to dry completely between waterings; drought tolerant.
Soil: Extremely well-draining, gritty cactus and succulent mix.
Dormancy Period: Winter
Pet-Safe: No
Plant Size: Grown in 4" pot, shipped bare root.
 
Stenocactus phyllacanthus is a small, solitary (rarely offsetting) globular plant with numerous thin, wavy ribs and flattened, paper-like central spines that emerge from the areoles. It produces delicate, pale violet to white flowers with dark purple midstripes near the crown during the early spring months. In cultivation, it requires a site with bright direct sunlight and an extremely well-draining, gritty succulent soil, making it well-suited for container specimens or rock gardens due to its established drought tolerance. Its species name phyllacanthus combines Greek roots meaning "leaf-spined," referring to the broad, flat, leaf-like appearance of its central spines.  
 
Note: Visually very similar to Stenocactus multicostatus, but has less ribs.