Young aspens often don't survive because of factors such as grazing elk, according to a study by Northern Arizona University researchers.

or a one in 20 million chance of being killed by a tree in a public open space, according to Forest Research.

V. Phenotypic variation of trembling aspen of western North America. Forest Science 21, 319-328 (1976). Berveiller, D. & Damesin, D. Interspecific variability of stem photosynthesis among tree ...

The set of five stamps features individual leaves from the aspen ... and purple in fall. Its cinnamon-scented bark adds to its distinctiveness. The oak leaf stamp honors a forest cornerstone ...