apomorphy

noun

ap·​o·​mor·​phy ˈa-pə-ˌmȯr-fē 

plural apomorphies

biological taxonomy

: a specialized trait or character that is unique to a group or species : a character state (such as the presence of feathers) not present in an ancestral form

In this case, white flowers are a derived condition, an apomorphy, and red flowers are the ancestral condition.

—James D. Mauseth, Botany: An Introduction to Plant Biology, 2009

apomorphic

¦a-pə-¦mȯr-fik 

adjective

or less commonly apomorph

ˈa-pə-ˌmȯrf 

As far as possible, it is assumed that each apomorphic evolutionary event only occurred once in the history of each group of related taxa …

—C. Barry Cox and Peter D. Moore, Biogeography: An Ecological and Evolutionary Approach, 2010

… such apomorph characters are believed to be found only among the descendants of the ancestor in which the character first occurred.

—Ernst Mayr, The Growth of Biological Thought, 1982

Word History

Etymology

apomorphic or apomorphous (borrowed from German apomorph, from apo- "away from, apo-" + -morph "having such a structure, -morphous) + -y entry 2

First Known Use

1969, in the meaning defined above

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