Evolutionary taxonomy or
evolutionary systematics seeks to classify
organisms using a combination of
phylogenetic relationship and overall similarity. It differs from strict
cladism where all
taxa in a classification always should include all descendants of a single ancestral node. It thus allows for
paraphyletic taxa. As evolutionary systematicists define terms, paraphyletic taxa are
monophyletic too, in the sense that they derive from a single common ancestor, just not
holophyletic, meaning that all descendants are included (which is monophyletic according to the cladistic definition).