heteromorphism

from The Century Dictionary.

• noun The state or character of being heteromorphic; deviation from a type or norm, or from congruity.
• noun In biology, the property of replacing lost parts by new parts which are different from those that have been lost. See heteromorphosis.

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

• noun (Biol.) The state or quality of being heteromorphic.

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

• noun A diversity of form.
• noun A feature that is heteromorphic.