Mexican Lime Cactus, Fire Barrel, Mexican Fire Barrel Cactus . Mexican Lime Cactus or Mexican Fire Barrel (Ferocactus pilosus) (Werdermann): A large barrel cactus that sports funky, pink spines.This species has 13-20 ribs lined with red to pink spines. Being such an impressive species, it's known by several English names, including Mexican Lime Cactus, Mexican Fire Barrel Cactus, and just plain Fire Barrel. Ferocactus pilosus Blessed with fantastic coral red spines and white hairs on the areoles. Initially globe-shaped, plants eventually grow tall. Endemic to Mexico, it’s best grown in temperate climates as a houseplant, where it makes an interesting feature in the conservatory or windowsill. Description: F. stainesii is a simple or clumping barrel/column cactus with thick red spines. Ferocactus pilosus. Click on the pictures for full plant details and prices. In the end, it was those reddish spines at the cactus's top that enabled me to identify it in Alfredo Flores's Guía de Cactáceas del Estado de Coahuila as FEROCACTUS STAINESII ssp PILOSUS. Ferocactus pilosus . In the wild, mature plants can reach up to 10.0' tall and 20.0" in diameter. Ferocactus pilosus is a striking barrel cactus with thick red spines.