We are immensely grateful for the help of so many people during this project. Translators, hobbyists, commercial growers and scientists were most generous with the help. Japanese botanists Norio Sahashi, Toshiyuki Nakaike and Haruki Hirabayashi have been of invaluable assistance throughout a number of years in the exchange of extensive correspondence and by providing us with much of the literature otherwise not available to us. In the summer of 1993, we had the privilege of joining many other Japanese botanists in the field in southern Japan where we were made familiar with many of the native fern species, including a large number of Dryopteris. We are indebted to these botanists, particularly Mituyasu Hasebe, Noriaki Murakami, and Shigeo Masuyama. We are specially grateful to Keisuke Yasuda for his patience and good humor in pointing out to us the Dryopteris species and in later sending us specimens of species which we had not been able to see in the field. Wu Su-gong of China was able to confirm the identity of a particularly troublesome species. Rose Murphy and Christopher Page of England kindly shared with us their expertise on the British species.

We would also like to thank Alan R. Smith, University California at Berkeley (UC), for allowing us the use of the herbarium facilities. The herbarium of the New York Botanical Garden kindly provided us with the loan of some American and European species. We acknowledge, also with gratitude, the use of the facilities of the herbaria of the University of California, Los Angeles, California State University, Northridge, Natural History Museum of Los Angeles County, and of the Missouri Botanical Garden.

We relied heavily on the publications and the personal counsel of Christopher Fraser-Jenkins. He has always been available to identify specimens that puzzled us. He has also reviewed our manuscript and suggested revisions and corrections; we are greatly indebted to his efforts. Any errors in this publication, however, are entirely our own.

There were contributions from many growers that made this work possible. Carl Starker of Oregon, now deceased, sent us herbarium specimens which helped document the species and cultivars in early cultivation. Comparative specimens were provided by Chris Goudey of Australia and Roy Vail of Arkansas and the Rhododendron Species Foundation and Hardy Fern Foundation of Washington. We are particularly appreciative of Judith Jones of Fancy Fronds, Washington, for providing both live plants and herbarium material throughout this study. Naud Burnett of Casa Flora, Texas, kindly provided assistance in publication.

We gratefully acknowledge the assistance of Robbin Moran of the New York Botanical Garden, and Robin Halley, Bob Halley and Phyllis Bates of the San Diego Fern Society, who reviewed this paper and provided us with corrections and many helpful editorial suggestions.