Taxonomic and Genetic Studies on the Cultivated Peppers, Capsicum annuum L. and C. frutescens L.

Abstract

Linnaeus originally proposed two species of Capsicum-C. annuum and C. frutescens. Since that time there has been no agreement as to whether the principal cultivated peppers constitute one or two species. As a result of our studies, we believe that both C. annuum and C. frutescens are valid species and that they cannot be combined into one species, as originally proposed by Bailey (1923). Because of the great variation present in both, the two species are morphologically somewhat difficult to distinguish. However, C. annuum normally has white corollas and single pedicels, whereas C. frutescens has waxy, greenish-white corollas and frequently paired (or even three to six) pedicels at the nodes. Of the varieties of peppers now in commercial cultivation in the United States, all but Tabasco are referred to as C. annuum. Both species have the diploid chromosome number of twenty-four. Genetically, we have found the two species to be highly cross-sterile, although there is conflicting evidence in the literature. We have secured no viable seeds in interspecific crosses when C. annuum has been used as the female parent, and only a very low percentage of viable seed when C. frutescens has been used as the female parent. On the other hand, fertile F1 plants have been readily obtained in numerous crosses within each species. The one F1 hybrid between the two species that has set fruit showed some reduction in percentage of good pollen present, moderate self-fertility, very low cross-fertility with either parent.