"I perhaps owe it to flowers," wrote Claude Monet (1840-1926), "that I became a painter." His fascination with trees, while perhaps of equal intensity, is less well-documented. One of the leading figures of the Impressionist movement and perhaps the most celebrated landscape painter of his age, Monet dedicated his life to capturing the subtleties of the natural world. Trees--willows enveloped in the eerie mists of the Seine, palm trees beneath the...