polyphyletic

from The American Heritage® Dictionary of the English Language, 5th Edition.

• adjective Of or relating to a group of taxa that does not include the common ancestor of all the members.
• adjective Of or derived from more than one stock or source.

from The Century Dictionary.

• Pertaining to or derived from several phyla; having several different lines of descent: as, a polyphyletic origin.
• Of or pertaining to the doctrine or theory that animals are not monophyletic, but are severally and specially created, or at least derived from many different sources.

from the GNU version of the Collaborative International Dictionary of English.

• adjective (Biol.) Pertaining to, or characterized by, descent from more than one root form, or from many different root forms; polygenetic; -- opposed to monophyletic.

from Wiktionary, Creative Commons Attribution/Share-Alike License.

• adjective biology Having multiple ancestral sources; referring to a taxon that does not contain the most recent common ancestor of its members.