1. Department of Biological Sciences, Boise State University , Boise, ID 83725, USA
2. University of Idaho , Moscow, ID 83844, USA
3. Forest and Rangeland Ecosystem Science Center, United States Geological Survey , Boise, ID 83706, USA
4. Royal Botanic Gardens , Richmond TW9 3AE, UK
5. Institut Botànic de Barcelona (IBB, CSIC-Ajuntament de Barcelona) , Barcelona 08038, Spain
6. Rocky Mountain Research Station, United States Forest Service , Moscow, ID 83843, USA