The true origin of this word is unknown, though the word was first used by
William Jackson Hooker without any elaboration to describe
Melocactus intortus. However, he also used the word to describe the hair flower buds of cacti such as
Echinopsis, which currently are not considered cephalium-bearing. According to
Karl Moritz Schumann, the genera
Melocactus and
Cephalocereus—which by today's standards does not bear a true cephalium— are the only genera that have cephalia.
Facheiroa and
Micranthocereus have also been classified as cephalium-bearing cacti.
Alwin Berger,
Nathaniel Lord Britton and
Joseph Nelson Rose consider
Discocactus and
Melocactus to be the only true cephalium-bearing cacti. Few even consider the areoles of
Neoraimondia and
Neoabbottia as cephalia. == Pseudocephalium ==