Embryophytes have Equivalent Sexual Phenotypes and Breeding Systems: Why Not a Common Terminology to Describe Them?

Abstract

From our review of the literature it is clear that bryophytes, pteridophytes, and flowering plants, indeed most embryophytes, have equivalent sexual phenotypes and mating/breeding systems. We demonstrate that these phenotypes can be described with a common terminology, even though the reproductive structures of the groups are quite different. We consider morphological, functional, and temporal phenotypes and recommend the use of common terms such as unisexual, bisexual, male, female, and hermaphroditic in lieu of taxon-specific terms such as monoclinous, staminate, and perichaetial. We use self- and cross-fertilization and self- and cross-pollination to describe those processes. Likewise, inbreeding, mixed-breeding, and outbreeding can be used to describe breeding systems. Automixis, autogamy, facultative xenogamy, and xenogamy provide a more precise circumscription of mating/breeding systems. The use of well-known terms and a common terminology should improve communication among systematists, reproductive biologists, and/or evolutionary biologists, whether they work with bryophytes, pteridophytes, gymnosperms, or angiosperms, and with the broader biological community.