What We Do (and Don't) Know About Ferns: Dryopteris (Dryopteridaceae) as a Case Study

Ferns are the second largest group of vascular land plants after the angiosperms, but remain chronically underrepresented in studies of plant phylogeny, biogeography, physiology, and genomics. The genus Dryopteris, the woodferns, is a large group with a worldwide distribution, and recent research has made it one of the better understood fern genera and a potential model for understanding many aspects of fern biology and evolution. Here we review historical and current understanding of the genus, and outline promising avenues of future research in ferns for which Dryopteris is an ideal study system, particularly for research on polyploid complexes, biogeographic distributions, and physiological ecology.