Aspen clones vary in size from only a few stems, to many thousands encompassing several acres. Cloned aspen stands are frequently easy to pick out. These groves tend to be round in shape with the oldest stems in the middle, and youngest around the outside. Due to the identical genetic makeup of these trees, they also exhibit the same characteristics, the most notable of which is autumn leaf color. This hillside mosaic in Alaska displays a collection of cloned aspen groves distinguishable by their slightly differing colors. Under optimal conditions, single groves of aspen may cover many acres. The largest of these groves may technically comprise the world's largest living organism.