Aspen, one of the few broad-leaved trees to grow ... which in turn form oozing bruises under the bark. On another tree, Worrall finds small cracks like those on the surface of a cookie, a clue ...

While it is not one of the tallest, Pando is the world's largest tree and one of the oldest living organisms, which is one of the reasons it is so fascinating and worth seeing in person. The clonal ...