Photo taken in St. Martin/Caribbean
Melocactus (melon cactus) is a genus of cactus with about 30-40 species. They are native to the Caribbean, western Mexico through Central America to northern South America.
At maturity, Melocactus begin to develop a cephalium, which is a dense mass of areoles that form a bizarre, bristly “cap” directly on top of the stem. Once this cap is formed, the stem no longer grows, but the cephalium will continue to grow until the plant dies. In rare cases, the cephalium can exceed 3 feet (1m) in height.