During the summers of 1956-1958, the writer continued the collection of material for a comprehensive adventive flora of St. Louis (Miihlenbach, 1957). Again, a number of species not previously recorded for Missouri have been discovered. Thirty-three (omitting several not positively determined) are published in the following list. They were without exception, collected within the city limits of St. Louis. The writer wishes to express his appreciation for their assistance to Drs. F. J. Hermann, I. M. Johnston, J. Sauer, G. B. Van Schaack and J. A. Steyermark. Specimens verifying these records have been deposited in the herbarium of the Missouri Botanical Garden. The initials and numbers in parentheses below are those of the writer in field collections.