Cephalium is a, frequently brightly coloured, structure of wool and bristle at the growing tip of certain cacti. It is most commonly found on cacti of the genus Melocactus and can take a number of colours, forms and shapes. The cephalium will only begin growing after a cactus has reached a certain size or age. Once flowering begins the flower buds will form from the cephalium.
This Cactaceae article is a stub. You can help Wikipedia by expanding it.