Thirty-one strains of crested wheatgrass from European and North American sources were assigned to six morphological forms. These forms showed affinities to the species Agropyron cristatum (L.) Gaertn., A. desertorum (Fisch.) Roem. & Schult., A. sibiricum (Willd.) P.B., A. fragils (Roth.) Nevski, A. michnoi Roshev., and A. imbricatum (M.B.) Roem. & Schult. Typical plants, spikes, glumes, and seeds of the six forms were illustrated. Eight strains of A. cristatum were diploid (2n = 14) and two strains were tetraploid (2n = 28). Strains of all other forms were tetraploid. Chromosome counts of root tips indicated no aneuploids in 71 diploid plants and one aneuploid (2n = 29) in 96 tetraploid plants. Meiotic observations, however, indicated accessory chromosomes in 14 of 43 tetraploid plants. Diploid forms of A. cristatum crossed sparingly with tetraploid species to form sterile hybrids. All tetraploid species were interfertile and formed fertile hybrids. Most desirable strains agronomically were of the species A. cristatum, A. desertorum, and A. imbricatum. Most vigorous hybrids were sterile plants from crosses of A. desertorum and A. cristatum.