The Tree (30 page)

The Ericaceae family, for whom the whole order is named, is also full of good things. Defined broadly (as Judd does) it now includes 2,700 species in 130 genera of vines and shrubs as well as trees. They grow almost worldwide (although they never made it to Australia—at least as wild plants), especially on uplands and typically on acid soils, relying very heavily on the mycorrhizal fungi in their roots. A few are epiphytes. Some have evolved into parasites and have abandoned chlorophyll. The Scots at the edge of Europe’s tundra know the family mainly for
Calluna,
the heather, the stuff of purple hillsides. But
Calluna
is but a windswept northern outlier. The related heaths in the genus
Erica
are particularly various in South Africa (which has 450 species), and grow to at least head height.

Where exactly the Ericaceae first arose is not clear, but the Himalayas is a good bet. At least 700 of the 1,200 species of
Rhododendron
and related
Pieris
grow where some of the world’s mightiest rivers begin—the Brahmaputra, the Mekong, the Yangtze—and many achieve tree-like dimensions, though since they have many stems they are generally rated as shrubs. There are another 300 species in New Guinea, which are apparently an offshoot of the original Himalayans. Rhododendrons are considered bad news in Britain, where they grow as wild and rampant exotics, though they provide excellent nesting grounds for buzzards.

Arbutus
is the genus of the strawberry tree and of the lovely madrones of North America—with smooth red bark that peels away to reveal yellow-gray beneath. I have walked among madrones in the hills of California, north of San Francisco: they are among the glories of a glorious landscape. Deer and quail enjoy their orange-red fruits. So, too, did the Native Americans. The wood is used locally and makes fine charcoal. Madrones do not grow big, but they can live for at least two hundred years.

In the Lecythidaceae family are some of the world’s greatest, most intriguing, and most economically important trees. The family includes 400 or so species in 30 genera—of shrubs and vines as well as trees; they are centered in South America but also found in Africa, Madagascar, and tropical Asia. The smallest of all is the eccentric
Eschweilera nana,
which grows out in the Cerrado and often has an underground trunk like the
Attalea
palm, a device that protects against fires. Many, however, are emergent trees that grow through the canopy to tower above the rest. Tallest of all are
Cariniana micrantha
and
Couratari stellata,
both up to 60 meters.
Cariniana
and
Couratari
have the sky to themselves and are pollinated by wind, which is unusual among tropical trees (and among Lecythidaceae). The long, straight boles of
Cariniana
make excellent timber, and forest hunters tip their arrows with a poison from the bark of
Cariniana domestica. Cariniana
is the longest-lived of the Lecythidaceae—indeed, of all the neotropical trees. Some have been dated at fourteen hundred years.

Most striking, however, are the fruits of many of the Lecythidaceae: big wooden globes and cylinders, generally born directly from the trunk, and packed with seeds. The wooden armor has evolved, presumably, to deter predators, although the capuchin monkeys of Amazonia sometimes get the better of it. Sometimes the seeds are big and fleshy and eminently edible, and are dispersed by animals—sometimes by fish. But in some genera (like
Carinaria
) the seeds are winged like those of an ash and, when the casing breaks, are dispersed by wind. These seeds are too light to carry much nutrient, and to make up for this the seed leaves are green and begin to photosynthesize the moment the seeds germinate.

Most important by far to human beings is the Brazil nut,
Bertholettia excelsa—
up to two dozen triangular, desperately hard nuts packed like the segments of an orange within their desperately hard casing. The Brazil nut tree is almost as tall as
Carinaria.
It can provide good timber, but few would cut it for such a purpose. It’s the nuts that matter: they are 66 percent fat and 14 percent protein—and, more to the point, their flavor is sublime. Europeans and North Americans import about fifty thousand tons of them a year from Brazil and Venezuela, some from wild trees but also from plantations, not least around Belém, at the mouth of the Amazon. The wild trees are protected, and often these days you see them gaunt and abandoned in the middle of nowhere: over vast areas the rest of the forest, which they have evolved to look down upon, has been cleared to make way for sun-stressed cattle and soybeans. Brazil nut trees are very susceptible to fire, and although they are huge they are not long-lived (in contrast to
Cariniana
). The biggest of them are less than three centuries old.

The wooden orb that encloses the Brazil nuts has a neat cap at the top, which comes off when the fruit falls to the ground. But the nuts remain trapped: the Brazil nut tree at this point relies upon the good offices of the agoutis, which are long-legged relatives of the guinea pig, to make the hole bigger and carry the seeds away. The agouti eats some of the nuts and buries others for later, just as a squirrel buries acorns (such stashing is a very rodent trick). It doesn’t recover all of them, however, and the seeds that it forgets grow into new trees—though they take twelve to eighteen months to germinate. Thus the Brazil nut tree relies not simply upon the agouti but upon the agouti’s amnesia. The empty Brazil nut cases fill with rainwater and then form nurseries for insects and frogs.

The
Lecythis
genus produces sapucaia or paradise nuts, which are said to taste even better than Brazils. I cannot vouch for their excellence; I wish I could. Clearly there is another market here—another economic reason for conserving the Brazilian forest, rather than cutting it down, to add to its aesthetic and ecological advantages. The wooden spheres that enclose the nuts are known as “monkey pots.” Apparently you can catch monkeys by putting a sweetmeat inside an empty pot. The monkey comes along and grabs it, cannot withdraw its closed fist, and refuses to release its booty even when the hunter comes along to bop it on the head. Monkeys are standard fare for the people of tropical forests.
Lecythis pisonis,
of Amazonia and the Brazilian Atlantic forest, has the largest fruits of all the family: it takes them about a year to grow as big as your head. The fruit opens while still on the tree to reveal seeds that are each coated in a bright fleshy aril. On the same night that the fruits open, the seeds are dispersed by bats. The efficiency both of animal pollination and seed dispersal can be staggering: coevolution really works. The flowers of
L. pisonis
are pollinated by carpenter bees, which are among the biggest bees of all (even bigger than bumblebees).
L. grandiflora
yields a much-valued timber marketed as wadadura.

The wooden fruits of
Couroupita guianensis
grow straight out from the trunk and may be twenty centimeters (nearly eight inches) across, giving it the name of “cannonball tree.” The fruits break as they hit the ground to expose a bluish-green pulp, packed with hairy seeds. To people the pulp smells foul, but peccaries (American wild pigs) love it. The seeds, or some of them at least, pass right through the peccary, apparently protected from its digestive juices by their hairiness, and may germinate in the dung. The pulp of cannonball trees is also fed to domestic pigs and poultry. The cannonball tree is often grown as an ornamental: its intriguing fruits follow a show of large, waxy, sweet-smelling flowers.

Also grown as ornamentals are species of
Barringtonia,
the most important genus from the Old World.
Careya,
of Malaysia and India, gives useful timber known as tummy wood.

N
IGHTSHADE
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ORAGE
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OLANALES

It isn’t a hundred percent clear that the Solanales does form a coherent group, a true clade. For the time being, however, the order is taken to include around 7,400 species of herbs, shrubs, vines, and trees in six families, of which three are of particular interest.

The Solanaceae are the family of potatoes, tomatoes, capsicums, and eggplants. All are pharmacologically potent, at least in the wild form: wild potatoes and tomatoes are generally poisonous. Also in the family, as if to rub the point home, are tobacco, mandrake, and the nightshades. The shrub jimsonweed
(Datura)
provides steroids that are used to prepare oral contraceptives. Only a few Solanaceae are trees, however. I have seen some of them out in the Cerrado. Attractive, but not large.

The family Boraginaceae may or may not belong among the Solanales. Its position, says Judd, is “somewhat problematic.” In any case, it includes 2,650 species in 134 genera of herbs (including borage and comfrey), vines, and shrubs, both tropical and temperate—and some very convincing and commercially significant trees. The 320 or so known species of the genus
Cordia
include
C. abyssynica
and
C. millenii
from East Africa and
C. platythyrsa
from West Africa, all marketed as “African cordia,” though all have euphonious local names as well. They grow up to thirty meters tall and up to a meter thick. The bole has an irregular shape, but the sapwood is a pleasant cream and the heartwood is golden brown, and although it is weak and soft it is good for decorative trimmings, like the edges of shelves in libraries, and for veneers. More to the point, it resonates well, and is favored for drums and sounding boards; and the people of West Africa make boats from cordia. Brazil has its own
Cordia: C. goeldiana,
known as freijo (or in Brazil as frei Jorge) and also, in the United States, as cordia wood or jenny wood. Some species of
Cordia
live around the coast, and their corky seeds are dispersed by water.

Cannonball fruits grow straight from the trunk.

C
OFFEE
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UININE
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IMBER
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ENTIANALES

Within the Gentianales order are four families containing about 14,200 species, with many excellent and important trees. The very large family of the Rubiaceae contains around 9,000 species in 550 genera. Most live in the tropics and subtropics, and most of the tropical species are trees or shrubs. They include many fine ornamentals, notably the much-valued
Gardenia,
some of which are trees in the wild. Most important by far of the many Rubiaceae that are pharmacologically significant is the genus of coffee,
Coffea. C. arabica
produces the best-quality coffee and is traditionally grown in tropical America, notably Brazil;
C. canophora
yields robusta coffees, which are generally less fine but higher yielding, and have been largely grown in Africa and Asia. Coffee is grown in various ways, but the quality is finest when the bushes are grown in shade, because then the fruits mature more slowly; the shade trees can be of many kinds, but leguminous types yield excellent fodder as a bonus. Everyone should do well out of coffee, but thanks to modern globalized trading laws all farmers in the tropics just about everywhere are now being exhorted to grow more and more of it—in places like East Timor and Vietnam as well as the traditional countries—so now there is a world glut: prices fell by nearly 70 percent in the five years up to 2004. Farmers borrow from banks or sometimes from moneylenders to start their coffee plantations, then find themselves selling for less than the cost of production and go bust (I have seen the failing plantations in eastern Brazil). Myth has it that the consumer benefits from their misery, but high street prices have not dropped noticeably; in truth, the only beneficiaries are the traders. ’Twas ever thus, it seems.

Several species of
Cinchona
were also of great pharmacological significance as the source of quinine, for a long time the frontline drug against malaria, much favored by the British colonialists. Whether the British obtained the rubber tree from Brazil by underhand means is somewhat arguable, but the removal of cinchona seeds from Bolivia in the nineteenth century was explicitly against Bolivian law. This seed founded the Javanese quinine industry, which dominated the world’s trade until 1939.

The Rubiaceae family also provides some fine timbers. Abura
(Mitragyna ciliata)
of the west coastal swamps of tropical West Africa grows to 30 meters and provides a pale yellow to pinkish-brown timber, excellent for moldings and floors, and also used to encase batteries because it is resistant to acid. Even taller, at around 50 meters, is the opepe,
Nauclea diderrichii.
Its creamy-pink sapwood and golden-yellow heartwood are valued both for their looks—for furniture, floors, turnery, veneers—and for rough work outside, from jetties to railway sleepers. Degame,
Calycophyllum candidissimum,
from Cuba, Mexico, Venezuela, and Colombia, is smaller than its African cousins (up to 20 meters tall) but again excellent for sculpture, turnery, furniture, and floors.