Aspen trees start growing fast at the start of summer and drop their leaves in winter but are alive and require metabolic energy. They have a white outer bark which is a thin photosynthetic green layer. The bark allows the tree to synthesize sugars and keep growing even in the winter when all other deciduous trees go into dormancy. Due to the specialty of the bark of this tree. One of the amazing facts about the aspen tree is that it produces sugar and keeps growing even when other deciduous trees are mostly dormant. These trees live a very long life, individual aspen stems normally live about 60 to 80 years and sometimes for more than 150 years. Multiple stems of the tree can sprout from the same root system as each tree is part of a much large organism. When stems that are part of large clones die, they are replaced with new growth. That’s why even a single stem has a short lifespan, but the entire clone can live for more than ten thousand years.