closeup of the stems of a old man cactus, white bearded cactus, endangered plant specie from mexico

closeup stems old man cactus white bearded endangered plant specie mexico cephalocereus senilis grey gray beard species threatened tropical exotic mexican america american arid dry desert plants shaggy coat coated silver flowering cactuses cactaceae columnar stem green popular horticulture garden gardening ornamental decorative cultivated cultivation botany nature background hairy