Leo Hitchcock, Arthur Cronquist, Marion Ownbey, and J. W. Thompson, and published serially from 1955 to 1969 by the University of Washington Press as volume 17 of the University of Washington Publications in Biology. The sequence of families is the same in the two works except for the transposition of the monocotyledons and dicotyledons; the dicotyledons are in the traditional Englerian sequence, and the monocotyledons are arranged according to the system of Cronquist as presented in "The Evolution and Classification of Flowering Plants." The genera within each family in this manual are alphabetically arranged, as in the earlier work, but for convenience in presentation it has bee necessary to number the species.