  This paper generalizes the operadic construction of the Connes-Kreimer Hopf
algebra of rooted trees by Moerdijk. Examples of Hopf algebras obtained in this
way include the Loday-Ronco Hopf algebra of planar binary trees and the
Brouder-Frabetti pruning Hopf algebra. In some examples we obtain a natural
pre-Lie or dendriform algebra structure on the dual Hopf algebra. v2: Proof in
section 8 corrected. v3: more corrections.
