North American Species of Sclerotinia—I

Some ten years ago the writer agreed to undertake the preparation of a monograph on the species of Sclerotinia for the North American Flora published by The New York Botanical Garden. A survey of the species reported from North America up to that time led the writer to assume that the undertaking would be a relatively simple one. His limited experience in taxonomic work was also doubtless an important factor in luring him into what promises to be a long and laborious though a most interesting and enjoyable investigation. It soon became apparent that to prepare a careful and reliable presentation of the North American species in this genus would require not only the collection and the examination in fresh condition of the morphology of as many of the forms as possible but also a comparative study of these forms in pure culture. Collecting soon uncovered undescribed species of Sclerotinia and species not heretofore reported from this country. The numbers of these have now increased to such an extent and the results of