The Melocactus table at B&B Cactus Farm, Tucson
Native to a large region including Mexico, Central America, the Caribbean and northern South America, Melocactus includes around 40 species. Found in European collections as early as the 1500s, Melocactus was most likely the first cactus encountered by the early Spanish explorers. It's beauty lies in the magnificent spination, plump cylindrical body and colorful cephalium which can take anywhere from 5 or more years to develop. The cephalium eventually grows tall (to 18 inches plus) and cylindrical and looks a bit like a hat, hence the common name for many species "Turks Cap".
Once mature, Melocacti put most of their energy into the cephalium. The cephalium has evolved as a method to protect the young flower buds and fruits from sun, cold and foraging animals. After flowering the pollinated flower retracts into the cephalium where the fruit can develop in safety. Once ripe the fruit pops up out of the cephalium where it can be seen and eaten by hungry birds or in some cases lizards who disperse the seed in their droppings. Seed is usually the only method of propagation as Melocactus are usually solitary, though some may form offsets when very old.
Melocactus are native to tropical regions and appreciate more water and humidity than might be expected of a cacti, though they still require a well drained soil. Water regularly in the hot summer months and spritz them with a little distilled water now and then if you live in a hot dry climate like mine. They also dislike cold and should be sheltered in the winter and watered sparingly.