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Research and Conservation in Southern Sonora, Mexico

Pilosocereus alensis (Sonoran old man cactus, woolly torch, pitahaya barbona)
syn. Cephalocereus alensis

This is the only cactus in our region with a pseudocephalium (tufts of hairs that grow out of one side of mature stems). The hairs protect the flower buds. Flowers open at night in June and give off the odor of ammonia, attracting bats for pollination. The juicy fruit is tasty.


Pilosocereus alensis in tropical deciduous forest near Alamos, Sonora. Photo: Mark Dimmitt

The pseudocephalium of Pilosocereus alensis. Photo: T.R. Van Devender


The nocturnal flowers of Pilosocereus alensis remain open until shortly after sunrise. Photo: Mark Dimmitt

Fruit of Pilosocereus alensis. Both flowers and fruit have the unique(?) trait of turning black when dry. Photo: Mark Dimmitt

Dense tropical deciduous forest from Sonora and Chihuahua south to Jalisco. If the forest is cleared around these plants, they will sunburn severely.