Although all names (approximately 350,000) encountered in the original literature survey were cataloged and included within the BONAP database, many are no longer used or are of questionable application. These omitted names are primarily found in older works such as as Flora of the Southeastern United States (Small 1903), Flora of the Rocky Mountains and Adjacent Plains (Rydberg 1922), Flora of Utah and Nevada (Tidestrom 1925), Flora of the Prairies and Plains of Central North America (Rydberg 1932), and Ferns of the Southeastern States (Small 1938). Additionally, anomalous names and the names of a number of cultivated plants with unconfirmed occurrences outside cultivation are excluded from the Taxonomic Data Center.