Patricio Robles Gil / Giant barrel cactus (Ferocactus diguetii) in flower on coast, Catalina Island, Gulf of California, Mexico

Patricio Robles Gil / Giant barrel cactus (Ferocactus diguetii) in flower on coast, Catalina Island, Gulf of California, Mexico

Tim Fitzharris / Saguaro (Carnegiea gigantea) and Giant Barrel Cactus (Ferocactus diguetii) with Panther and Safford Peaks in distance, Saguaro National Park, Arizona

Tui De Roy / Giant Barrel Cactus (Ferocactus diguetii) in bloom, Santa Catalina Island, Sea of Cortez, Baja California, Mexico

Tui De Roy / Giant Barrel Cactus (Ferocactus diguetii) detail of spines, Santa Catalina Island, Sea of Cortez, Baja California, Mexico

Tim Fitzharris / Saguaro (Carnegiea gigantea) and Giant Barrel Cactus (Ferocactus diguetii) with Panther and Safford Peaks in distance, Saguaro National Park, Arizona

Patricio Robles Gil / Giant Barrel Cactus (Ferocactus diguetii) and Agave (Agave sp) in Miquihuana Desert, part of the Great Chihuahuan Desert in Tamaulipas State, northeast Mexico