Pelargionium scabrum flower

The fourth episode in the history of plant evolution is marked by the emergence of flowering plants during the early Cretaceous period in the Mesozoic era, about 130 million years ago. The major difference of these new plants, or angiosperms, contrasted to gymnosperms, resides in the complexity of the reproductive structure. This new structure includes a flower bearing seed within protective chambers, called ovaries, as opposed to the naked seed that gymnosperms produce. The majority of modern plant species are represented by angiosperms, or flowering plants.