Three varieties of grain: rye, triticale, and wheat.

Hybridization is generally defined as the interbreeding of individuals from two populations or groups of populations that are distinguishable on the basis of one or more heritable characters. By extension, a hybrid is an individual resulting from such interbreeding. Hybrid zone refers to a region in which hybridization is occurring. Artificial hybridization refers to instances in which these crosses occur under controlled conditions, often under the direction of plant or animal breeders. In contrast, natural hybridization involves matings that occur in a natural setting.

Factors Limiting Natural Hybridization

A variety of factors serve as reproductive barriers among plant taxa. These barriers, which can be subdivided into those acting prior to fertilization (prezygotic) or following fertilization (postzygotic), restrict natural hybridization and help maintain species boundaries.

Prezygotic Barriers.

The potential for natural hybridization is largely determined by the...