Read The Tree for Free Online Page B

the United States and Canada just exceeds six hundred. Yet the New World tropics (the “neotropics”), stretching south from the Mexican border as far as Chile and Argentina, contain tens of thousands of species, sometimes with hundreds of different species per acre. Why the tropics are so much more various is discussed in Chapter 12.
    Meanwhile, two more immediate questions present themselves. First, how on earth can anyone—the most astute of hunters and gatherers or the most learned of professors—keep tabs on 350,000 or so species of plants, including around 60,000 trees? How can we begin to comprehend so many? Secondly, how did the enormous complexity that is entailed in being a tree come about? These matters are addressed in the next two chapters.

2
    Keeping Track
    W E SHARE THIS WORLD with millions of other species, and engage directly with many thousands of them—for food, shelter, medicines, aesthetic pleasure, and sometimes just because we need to stay out of their way. At least at a few stages removed,
all
of them affect us so some extent, and we in turn affect them. If we seek to exploit trees, or to conserve them, or simply to admire and appreciate them as they so richly deserve, we need first and foremost to know who’s who. So first we must try to identify and describe what species are out there. So far biologists have listed nearly two million—perhaps one in four of the total. Then we must ascribe a name to each, partly as an aide-mémoire, but mainly so as to communicate our findings with others. Third, we must classify: place the creatures we have identified into groups, and then nest those groups in larger groups, and so on. Without classification, naming becomes ad hoc, and we could not hope to keep track of more than a few hundred different kinds, and probably a lot fewer.
    The reasons for all this endeavor are not purely practical. Science is an aesthetic and spiritual pursuit. The more that is revealed, the more wondrous nature becomes. The more we know about living creatures, the more deeply we can engage with them. This is the appetite, as Hamlet said, that grows from what it feeds on.
    But the problems of identification, naming, and classification are many and diverse. This, after all, was the first task that God gave to Adam (Genesis 2:19), and although a lot of Adam’s descendants have been hard at it ever since, there’s still an awfully long way to go.

    How can we make sense of so much diversity?
    WHO’S WHO?
    Identification is the beginning of all natural history. Nature appears to us as the grandest conceivable theater, endlessly unfolding. There can be no understanding at all until we have at least some inkling of the cast. We must be able—again to quote Hamlet—to tell a hawk from a handsaw.
    But identification can be difficult for all kinds of reasons—even identification of trees, which are so big and conspicuous, and which do not run away. We have already seen the practical problem posed by some willows: that both leaves and flowers may be needed for identification but the two may not be present at the same time. Yet whatever problems may confront us in temperate climes, we can be sure that the tropics will pose far worse. In tropical forests, flowers, which are the principal guide to botanical identification, are usually absent. In seasonal rain forests (with a distinct wet and dry season), many trees gear their flowering to the rains, so flowering is to some extent predictable. But much rain forest (as in much of Amazonia) is nonseasonal, and trees may flower at any time. To be sure, different trees of the same species generally flower simultaneously, for if they did not, they could not pollinate each other. So they must be responding to signals from the environment at large, or else (or in addition) they must be communicating with one another. But what those signals are is unknown, at least to us. To the human observer, the flowering seems random. In any case, in a