A cultigen is a cultivated species of plant that does not have a known counterpart occurring naturally in the wild; that is to say, a species that evolved through human intervention. The term was coined by biologist Liberty Hyde Bailey in 1918; he shortly thereafter coined the term cultivar to describe a plant that was distinct from wild varieties but not yet a separate species.
"Plant or group known only in cultivation; presumably originating under domestication; contrast with indigen"
--Manual of Cultivated Plants by Liberty Hyde Bailey (1924)
Examples of cultigens include the banana, the banana squash, corn (maize), beans, and cabbage.