Trees have the distinction of being the largest and oldest living organisms on earth. Although the herbaceous habit has made unprecedented evolutionary gains since the middle and late Cenozoic, trees still are the most conspicuous plants covering the habitable land surface of the earth. Man has long sought their shelter and protection, utilized their food and fiber, and often exploited them to his own detriment. Trees have always been of much interest to botanists, and many of the early investigations concerning the structure and function of plants were conducted with trees. At the beginning...