Live root material of leafy spurge (Euphorbia spp.) was collected from 38 locations across northern United States, southern Canada, and from 1 location in Austria. These materials were established in a nursery at Lincoln, Nebraska along with E. agraria M. Bieb. and E. cyparissias L. # EPHCY. Nineteen vegetative and reproductive characters, taken from various taxonomic keys, were measured on plants established for a period of 3 yr. Data were compared with previous taxonomic keys of Euphorbia species. A key developed by A. Radcliffe-Smith was used to separate the nursery entries. Leaf width measurements were the most useful taxonomic criteria. Five morphologically separable taxa were observed: E. × pseudovirgata (Schur) Soó, E. esula L. # EPHES, E. uralensis Fisch. ex Link., E. agraria M. Bieb., and E. cyparissias L.
