2005605 Quaking Aspen (Populus
tremuloides) - USDA Illustration
USDA-NRCS PLANTS Database / Britton,
N.L., and A. Brown. 1913. Illustrated flora of the northern states and Canada.
Vol. 1
USDA, NRCS. 2024. The PLANTS Database (http://plants.usda.gov). National Plant Data Team, Greensboro, NC 27401-4901 USA.