Data collected on May 30, 2013 (dark bars; means separated by upper-case letters) and April 3, 2014 (light bars; means separated by lower-case letters). Included are six bluebunch wheatgrass (BBWG; native; blue bars), two Snake River wheatgrass (SRWG; native; red bars), and two crested wheatgrass (CWG; exotic; green bars) plant materials, each released in the year indicated within parentheses. The absence of a letter in common indicates significant differences among plant materials (P<0.05).