AT first glance it looks like another handsome horticulture book, lavishly illustrated with vivid colored plates of flowering shrubs, detailed botanical drawings, and black-and-white historical photographs and sketches. But A Reunion of Trees: The Discovery of Exotic Plants and Their Introduction into North American and European Landscapes (Cambridge, Mass.: Harvard University Press, 270 pp., $35) is more. Stephen Spongberg has written a grand adventure story about the migration of woody plants around the world and the men who collected and nurtured them. Particularly fascinating is the chapter about explorations in the Far East. The ginkgo tree was discovered by a doctor for the Dutch East India Company and is probably the first Asian tree to be widely cultivated in the West. It is a ``living fossil,'' a long-enduring plant form found in 225-million-year-old rock formations.
While many of the plants horticultural adventurers brought home were exotic indeed, some showed striking similarities to native species. Consider the two dogwoods pictured here. The individual seeds of the North American species are eaten by birds that help propagate new plants; the seeds of the Asian tree grow in large raspberry-like fruits that attract monkeys, which perform the same function. Over eons, the plants had adapted to their particular environments.
Both dogwoods now grow in the Arnold Arboretum in Boston, where many trees once separated by geology and time are now united - hence the title of the book. Spongberg is the horticultural taxonomist at the Arboretum. His history of botanical exploration manages to combine the excitement of discovery with the precise details of science. The result is a highly readable textbook - and if you visit the Arboretum, you can use the endpaper map to find the species described. This tale of the traveling trees is a treasure for both specialist and amateur alike.