RICKETT, Harold William (1896-1989). Wild Flowers of the United States. New York: McGraw-Hill Book Company, 1966-1973. 6 parts in 15 volumes (two copies of part one, volume I) with complete index, 4to (326 x 241 mm). Profusely illustrated with numerous colored plates and in-text drawings. (Minor spotting in some volumes.) Publisher's cloth of various colors, gilt-stamped spines, map endpapers in each volume with the region being discussed highlighted (lacking publisher's slipcases and glassine dust jackets, discreet library label on spine with associated markings). FIRST EDITION, second printing. Wild Flowers of the United States is divided by geographical region. Volume I: Northeastern states - Volume II: Southeastern states - Volume III: Texas - Volume IV: Southwest - Volume V: Northwest - Volume VI: Rocky Mountains and Great Plains and an Index.