Cereus houlletii

About

Pilosocereus leucocephalus, called old man cactus, old man of Mexico, tuno, and woolly torch, is a species of cactus in the genus Pilosocereus, native to Mexico and Central America. It has gained the Royal Horticultural Society's Award of Garden Merit. Pilosocereus leucocephalus functions as a keystone species in dry landscapes found in Mesoamerica. The fruit this cactus produces is relied upon as a source of hydration and sugar in arid areas by frugivores such as birds, bats, and even some reptiles.

Summary from Wikipedia