Some comments on the origin and evolution of conifers

Abstract

During the last several years there has been an increased emphasis on the study of conifer evolution including various aspects of their reproductive biology. The occurrence of similar stelar features as well as trends in the evolution of reproductive structures still point to cordaitalean affinities for the Coniferales. The evolutionary history of such families as the Pinaceae, Araucariaceae, and Taxodiaceae is beginning to be elucidated as well as that of certain extinct families including the Cheirolepidaceae and the Voltziaceae. Systematic investigations of fossil cone vasculature and resin canal distribution, leaf cuticles, seed integuments, and embryo structure not only have increased our knowledge of conifer evolution but also have led to changes in our views on the systematics of extant conifer groups.