ABSTRACT
Hybrid origin of a clade may be indicated by placing the multiplication sign in front of the name. The names of clades of hybrid origin otherwise follow the same rules as for other clades. An organism that is a hybrid between named clades may be indicated by placing the multiplication sign between the names of the clades; the whole expression is then called a hybrid formula. In cases in which it is not clear whether a set of hybrid organisms represents a clade, authors should consider whether a name is really needed, bearing in mind that formulae, though more cumbersome, are more informative.
