1. Dep. of Wildland Resources Utah State Univ. 5230 Old Main Hill Logan UT 84322–5230 USA
2. Current address: USDA‐ARS Northern Great Plains Research Laboratory PO Box 459 Mandan ND 58554 USA
3. USDA‐ARS Poisonous Plant Research Logan UT 84341 USA
4. USDA‐ARS Plains Area Administrative Office 2881 F and B Rd. College Station TX 77845 USA
5. Dep. of Plants, Soils and Climate Utah State Univ. 4820 Old Main Hill Logan UT 84322–4820 USA