The impact of Darwin and Haeckel led to new systems of botanical classification toward the end of the nineteenth century. In Germany much early interest developed, in part due to the influence of Haeckel, and this led to phylogenetic/evolutionary systems from Eichler and then Adolf Engler. Engler provided numerous perspectives on which groups were ancestral and which were derived, and these set a tone followed by most other workers into the twentieth century. Because of the morphological similarity of the gymnosperms to the wind-pollinated flowering plants (Amentiferae), these latter were regarded as ancestral within the angiosperms. Wettstein from Vienna offered a modified system, believing that Casuarinaceae might be the most primitive family. Hallier in Germany suggested that extinct gymnospermous Bennettitales perhaps gave rise to angiosperms (Magnoliaceae).