Actually its a succulent and its at the Desert Botanical Garden in Phoenix. But the postcard comes from Michigan.

cactus1

Desert Botanical Gardens, Papago Park, Phoenix, Arizona. The Boojum Tree, or Cirio, is a native of Baja California, resembles an inverted carrot, with very small branches. This tree is a member of the Candlewood family, which also includes the Ocotillo.