old man cactus in a tropical garden, grey bearded cactus, endangered plant specie from mexico

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