same species and might even have arisen from seeds produced by the same parents. And if you ask a grower or a forester how many kinds of trees there are, he or she may well suggest that the number is virtually infinite, since growers regard each of their cultivars as distinct and know that there could be as many different kinds as breeders care to produce.
So let us be more specific and ask, with what surely is irreducible simplicity, “How many
species
of trees are there?” At this point the biologists must surely stop prevaricating and provide a clear answer. But the only honest answer is: “Nobody knows.”
STILL COUNTING
In truth, we can never know for sure how many species of tree there are. As John Stuart Mill pointed out in the nineteenth century, it is impossible to know, in science, whether you know everything there is to know. However much you know, you can never be sure that nothing has escaped you. With trees, there are many good reasons to think that a great deal
has
escaped us. Every so often some highly conspicuous tree turns up that either has never been seen before or is known only from fossils and has long been presumed extinct. Two classic examples are discussed in Chapter 5: metasequoia, the dawn redwood, and
Wollemia nobilis,
regrettably dubbed the Wollemi pine.
But there is also a practical reason for ignorance. Most kinds of trees, like at least 90 percent of organisms of all kinds, live in tropical forests, and tropical forests are very difficult to study—largely because there are so many trees in the way. It requires hundreds of person-years, and heroic years at that, to list the species even in relatively small areas of tropical forest; and despite the best efforts of legal and illegal loggers, the tropical forest that remains to us is still mercifully vast—so that all of Switzerland, for example, could easily be lost in Amazonia. (Amazonia is the forest that surrounds the Amazon River; it occupies the western half of Brazil and extends into Peru, Colombia, Bolivia, and Ecuador. With a total area of more than 1.6 million square miles, it is about a hundred times bigger than Switzerland, which is a mere 16,000 square miles. Amazonia is also about sixteen times bigger than the United Kingdom, which is around 94,000 square miles.)
So it is that from the sixteenth century onward a succession of naturalists-cum-conquistadors, administrators, soldiers, traders, and priests became obsessed with the flora and fauna of tropical America and set out to identify, describe, and collect what was there. Dedicated research expeditions were mounted from the eighteenth century on, driven by scholarship and supported by empire and commerce—not least in search of new and valuable crops, of which rubber became the jewel. The greatest of all the explorers, so many believe, was the German Alexander von Humboldt, who, together with the French physician and amateur botanist Aimé Bonpland, traveled six thousand miles in South America between 1799 and 1804, on foot and by canoe. They collected 12,000 specimens of plants, including 3,000 new species, and hence doubled the number known from the Western Hemisphere. On their return they published the thirty volumes of
Voyage aux régions équinoxiales
at von Humboldt’s expense (it cost him his entire fortune), of which von Humboldt wrote twenty-nine volumes and Bonpland contributed just one, although von Humboldt insisted that they share the authorship of the whole. The book was first published in English between 1814 and 1829 in five volumes, as
Narrative of Travels to the Equinoctial Regions of the New Continent During the Years 1799–1804.
The great revolutionary Venezuelan general Simón Bolívar (1783–1830) commented that “Baron Humboldt did more for the Americas than all the conquistadores.”
The young Charles Darwin loved von Humboldt’s writings and in the 1830s carried the
Narrative
with him on his journey on the
Beagle
that changed his own life
So let us be more specific and ask, with what surely is irreducible simplicity, “How many
species
of trees are there?” At this point the biologists must surely stop prevaricating and provide a clear answer. But the only honest answer is: “Nobody knows.”
STILL COUNTING
In truth, we can never know for sure how many species of tree there are. As John Stuart Mill pointed out in the nineteenth century, it is impossible to know, in science, whether you know everything there is to know. However much you know, you can never be sure that nothing has escaped you. With trees, there are many good reasons to think that a great deal
has
escaped us. Every so often some highly conspicuous tree turns up that either has never been seen before or is known only from fossils and has long been presumed extinct. Two classic examples are discussed in Chapter 5: metasequoia, the dawn redwood, and
Wollemia nobilis,
regrettably dubbed the Wollemi pine.
But there is also a practical reason for ignorance. Most kinds of trees, like at least 90 percent of organisms of all kinds, live in tropical forests, and tropical forests are very difficult to study—largely because there are so many trees in the way. It requires hundreds of person-years, and heroic years at that, to list the species even in relatively small areas of tropical forest; and despite the best efforts of legal and illegal loggers, the tropical forest that remains to us is still mercifully vast—so that all of Switzerland, for example, could easily be lost in Amazonia. (Amazonia is the forest that surrounds the Amazon River; it occupies the western half of Brazil and extends into Peru, Colombia, Bolivia, and Ecuador. With a total area of more than 1.6 million square miles, it is about a hundred times bigger than Switzerland, which is a mere 16,000 square miles. Amazonia is also about sixteen times bigger than the United Kingdom, which is around 94,000 square miles.)
So it is that from the sixteenth century onward a succession of naturalists-cum-conquistadors, administrators, soldiers, traders, and priests became obsessed with the flora and fauna of tropical America and set out to identify, describe, and collect what was there. Dedicated research expeditions were mounted from the eighteenth century on, driven by scholarship and supported by empire and commerce—not least in search of new and valuable crops, of which rubber became the jewel. The greatest of all the explorers, so many believe, was the German Alexander von Humboldt, who, together with the French physician and amateur botanist Aimé Bonpland, traveled six thousand miles in South America between 1799 and 1804, on foot and by canoe. They collected 12,000 specimens of plants, including 3,000 new species, and hence doubled the number known from the Western Hemisphere. On their return they published the thirty volumes of
Voyage aux régions équinoxiales
at von Humboldt’s expense (it cost him his entire fortune), of which von Humboldt wrote twenty-nine volumes and Bonpland contributed just one, although von Humboldt insisted that they share the authorship of the whole. The book was first published in English between 1814 and 1829 in five volumes, as
Narrative of Travels to the Equinoctial Regions of the New Continent During the Years 1799–1804.
The great revolutionary Venezuelan general Simón Bolívar (1783–1830) commented that “Baron Humboldt did more for the Americas than all the conquistadores.”
The young Charles Darwin loved von Humboldt’s writings and in the 1830s carried the
Narrative
with him on his journey on the
Beagle
that changed his own life
Similar Books
Thin Air
Kate Thompson
The Last Justice
Anthony Franze
Wayward Soul
Kim Young, K. Renee
The Bare Bum Gang and the Football Face-Off
Anthony McGowan
To Run Across the Sea
Norman Lewis
The Seer's Choice: A Novella of the Golden City
J. Kathleen Cheney
Beyond the Sea
Melissa Bailey
The Hound of Rowan
Henry H. Neff
Biker Trials, The
Paul Cherry
Discourses and Selected Writings
Epictetus, Robert Dobbin