Etymology -A shortened form of the original name Echinomelocactus, which means "spiny apple thistle" .
Adult Melocactus are among the most fascinating of cactus in appearance. When young, the plants are quite plain and look very much like one would expect a cactus to look like. They have globose, green stems with multiple ribs. The spines are stout and usually feature a distinct central spine surrounded by radial spines resembling an asterisk. 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. Most cephaliums are white underneath and orange on top, but may be completely white. It is in this mass of areoles that the flowers are formed. The flowers themselves are quite small, typically pink and come out of the top of the cephalium sporadically or in rings. Many times, the flowers are not noticed by growers and it is only by the later appearance of fruit that proof of flowering is confirmed. The fruits are much more conspicuous than the flowers and are red or pink waxy-looking short tubes that many have likened to candles on top of a birthday cake. This illusion is further enhanced by the dried flower remains persisting and looking like the wick of these "candles".
Many Melocactus species are found in cultivation. They grow fairly easily from seed and as adults most prefer more tropical conditions with more moisture than other cacti and a low tolerance for cold. Despite their frequency in cultivation, identification of Melocactus species is arguably the most difficult of all globular cacti and is particularly difficult if not impossible before the cephalium is formed. Even with location data in the wild, ID is a challenge.
In habitat, Melocatus occur over a very large area including the Caribbean Islands, Mexico, Central America, and much of the north and central parts of South America.