This volume is the first published product of the Pennsylvania Flora Database, created & maintained at the Morris Arboretum of the Univ. of Pennsylvania. The database has its roots in the work of Edgar T. Wherry, John M. Fogg, Jr., & Herbert A. Wahl, the “Atlas of the Flora of Pennsylvania”, published by the Morris Arboretum. Over a period of 40 years, Wherry & his colleagues gathered data from the major Pennsylvania herbaria & manually placed a quarter of a million dots on over 3500 maps. The Pennsylvania Flora Database retains the emphasis on specimen-based, site-specific data. The checklist of included taxa has undergone extensive review to reflect recent taxonomic & nomenclatural revisions. Questionable specimens have been re-evaluated with the result that several taxa included in earlier works were dropped. Recent discoveries have been added & distribution data has been updated. This vol. also includes collections made in the 1990s in conjunction with the Pennsylvania Natural Diversity Inventory (PNDI), the state heritage program. The maps present the accumulated collection of information for each taxon as represented in the herbaria. Illus., reprinted 1996.