The Tree (28 page)

The tree with one of the lightest timbers of all (though not quite the lightest) is also from the Bombacaceae family: balsa,
Ochroma pyramidale,
native to tropical America from Mexico through to Brazil (and also Cuba), and now planted in India and Indonesia. Every child knows balsa as the stuff of model making. Grown-ups use it for rafts, aircraft, insulation, equipment for water sports, and, of course, for theater and film props, to reduce damage to actors. The main commercial source nowadays is Ecuador.

Finally we might mention the durian,
Durio zibethinus,
whose fruits are huge and spiky. Some find them delectable: another food for the gods. But they stink (shades of
Sterculia
again) and are expressly forbidden on airplanes.

In its new form, then—subsuming the Tiliaceae, Sterculiaceae, and Bombacaceae—the Malvaceae emerges as a truly remarkable family of truly remarkable trees. But the Malvales order also includes another arboreal family that is clearly discrete from the Malvaceae: the Dipterocarpaceae.

The dipterocarps are hugely various: 680 or so species in 16 or 17 genera (different taxonomists split them slightly differently). The principal genera are
Shorea
(by far the most important),
Dipterocarpus,
and
Dryobalanops.
Mostly the dipterocarps come from southern or Southeast Asia—Malaysia is the focus, with 465 species in 14 genera—but there are also 49 species in three genera in Africa, and one each in South America and the Seychelles. Between them the different types grow from coast to uplands in many (tropical) climates and in soil both fertile or—often—extremely infertile. Some grow on dry land, but on the whole they prefer the wet: there are many kinds in swamps, and the biggest grow where there is year-round moisture. I am told there is an old plantation of dipterocarps outside Kuala Lumpur, where many individuals exceed 60 meters.

Dipterocarp means “two-winged fruit”—and, indeed, they have fruits roughly like sycamore keys, though often much larger, and sometimes brightly colored. People make wide use of dipterocarps. The fruits of many
Shorea
and some
Dryobalanops
are boiled as vegetables. The seeds of both
Shorea
and
Pachycarpae
are extremely rich in fat—up to 70 percent—which is similar to cocoa butter though harder, and is much favored for chocolate and cosmetics. (And note again the loose phylogenetic relationship between the dipterocarps and the cacao tree, in the Sterculiaceae. Biochemistry runs in dynasties.) Most dipterocarps also produce useful resins; and a form of camphor comes from
Dryobalanops,
used as incense.

But above all, the dipterocarps dominate the international market in tropical timber.
Shorea
species from Southeast Asia are marketed as “meranti.” Various kinds are sold as light red or dark red meranti—red indeed and finely figured, and used for all purposes. Another group of
Shorea
feature as white or yellow meranti, also with many uses, from floors to ships, plywood, and veneers. Mersawa and krabak are two more, similar Southeast Asian timbers from the genus
Anisoptera.
Kapur from Malaysia and Indonesia is the genus
Dryobalanops.
Altogether, the Dipterocarpaceae are a formidable family—comparable in their part of the world with the oaks and beeches from farther north.

F
RANKINCENSE AND
M
YRRH
, O
RANGES AND
L
EMONS
, M
APLES
, M
AHOGANY
,
AND
N
EEM
: O
RDER
S
APINDALES

The Sapindales are closely related to the Malvales. As in the Malvales, reclassification is in train, so the traditional list of eleven Sapindales families is now reduced to eight. Six of those families—one of them now much expanded—contain trees that are at least intriguing, if minor (ecologically and economically), and others that are of supreme importance both in the wild and to humanity.

Minor but intriguing is the Simaroubaceae family, 100 species of trees and shrubs in 21 genera from throughout the tropics and subtropics. They are biochemically potent and widely deployed in medicine, especially
Quassia
from Africa, while
Picramnia
from the Americas was once exported to Europe to treat erysipelas and venereal disease. The white syringa of Africa,
Kirkia acuminata,
grows to 18 meters, provides useful timber, and also has swollen roots that store water, which knowledgeable locals tap in times of drought. Best known in the gardens and streets of the West is the tree of heaven,
Ailanthus altissima.
It was first imported to England from its native China in the mid-eighteenth century and thence to the rest of the West. It resists pollution, can grow to 30 meters in less than twenty years, and has compound feathery leaves like an ash, although each may be nearly a meter long.

Minor, too, by world standards is the Burseraceae family—but extremely intriguing, as the family of both frankincense and myrrh. In all there are about 500 species, in 17 genera, throughout the tropics but mainly in Malaysia, tropical America, and Africa, and many provide resins and aromatic oils for perfumes, soaps, paints, varnish, and incense. Frankincense comes from
Boswellia carteri,
of Somaliland; myrrh is from various
Commiphora
species, notably
C. abyssynica,
which grow and are now cultivated in Arabia and Ethiopia. The gifts of the Magi to the infant Christ in Bethlehem were exotic indeed. The first known government-sponsored plant-collecting expedition was in search of myrrh: reliefs on the Temple of Deir el Bahari at Karnak show myrrh trees being transported from the Land of Punt, around 1495
B.C.
The Burseraceae family also provides some useful timbers, widely used in Malaysia and Africa. Outstanding is gaboon of Africa,
Aucoumea klaineana,
used for everything from cigar boxes to sports gear and high-class furniture. Sometimes gaboon is mottled and striped, and then it is highly valued for veneers.

The Rutaceae family is named after the rue,
Ruta graveolens,
a small aromatic shrub, toxic but also medicinal, and grown in herbal gardens for centuries. It pops up here and there in the plays of Shakespeare, who surely was a competent naturalist, while his son-in-law was an outstanding apothecary. But the Rutaceae overall include about 900 species in 150 genera that grow throughout all the warmer reaches of all continents, including Australasia. By far the best known and important is the genus
Citrus: C. limon,
the lemon;
C. medica,
the citron;
C. aurantium,
the sour Seville orange—a variety of which is also the source of bergamot, the stuff of Earl Grey tea;
C. sinensis,
the ordinary, sweet orange;
C. reticulata,
different varieties of which are mandarins, satsumas, and tangerines;
C. aurantifolia,
the lime (not of course to be confused with
Tilia
); and
C. paradisa,
the grapefruit. Closely related to
Citrus
is
Fortunella,
the genus of the kumquat, which sometimes turns up pickled on smart dinner tables, though not in my opinion to very obvious advantage.

The Rutaceae also provide some valuable timbers. Various species of
Flindersia
feature as the cinnamon-colored “Queensland maple”—again for prestige furniture, gunstocks, oars, and what you will. Southern silver ash from eastern Australia,
F. schottiana,
is just as versatile but pale yellow. From South America comes pau marfin,
Balfourodendron riedelianum:
tough, pale, flexible; wonderful for oars, tool handles, shoe lasts, furniture, marquetry. Ceylon satinwood,
Chloroxylon swietenia,
from the southern Indian subcontinent, is called satinwood because it seems to shimmer like folded silk, and is highly prized for panels and veneers. Pale golden West Indian satinwood,
Fagara flava,
was used widely in the eighteenth century by the great English makers of fireplaces and furniture: Adam, Sheraton, and Hepplewhite.

But satinwoods have largely been ousted from favor by members of the Meliaceae family. The 51 genera (with 550 species) include several outstanding timber trees—indeed, their present and historical importance can hardly be overemphasized. The world star of the families for almost four centuries is the genus
Swietenia:
the American, or “true,” mahoganies. There are three species—closely related, and often hybridizing in the wild where their ranges overlap.
S. humilis,
with small leaves, prefers drier country, and spreads north into Mexico.
S. mahagoni,
the first of the trio to be named (by the Austrian botanist Gerard van Swieten) is from the Caribbean and southern Florida.
S. macrophylla,
the big-leaf mahogany from Brazil and Honduras, is the giant: an emergent tree, towering above the seasonally dry rain-forest canopy at about 70 meters, with huge buttress roots to reinforce a trunk that can be 3.5 meters in diameter.

Or this, at least, was the pristine state. There is little or no forest left where
S. mahagoni
and
S. humilis
once lived. The big-leaf mahogany is still to be found in the forests of southern Amazonia—anywhere between one big tree in every twenty-five acres to three trees per twenty-five acres—and might still, some say, be harvested sustainably and profitably from the wild. It is difficult to increase the proportion in the wild because mahoganies are light lovers and need open ground or clearings to get going. If they are simply planted among other trees they fail. But big-leaf mahogany and
S. mahagoni
are now widely grown in plantations, particularly in tropical Asia and Oceania, and increasingly in their homelands in the American tropics. Yet they have suffered enormously in plantations from an insect pest, the mahogany shoot borer, a species of
Hypsipyla,
which bores into the shoots and turns what should be a straight, proud tree into a mean shrub. The pest can be controlled; but largely because it is perceived as a problem, the world’s plantations of mahogany are only one-twentieth those of teak. Wild mahogany is now listed by CITES, and trade in general is more and more regulated. But it will be interesting to see what happens to mahogany, wild and cultivated, over the next few centuries.

Several close relatives of true mahogany are also fine timber trees: pride of India,
Melia azedarach;
African walnut,
Lovoa trichilioides;
South American cedar, species of
Cedrela;
Asian-Pacific red cedars, species of
Toona;
the sapele,
Entandrophragma cylindricum;
and other species of
Entandrophragma
and of
Khaya,
which are sometimes called “African mahogany.” Several trees that have nothing to do with the Meliaceae at all are also sold as “mahogany,” including several dipterocarps (of the genus
Shorea
) and the occasional eucalypt.

Less closely related to
Swietenia,
yet still within the Meliaceae, is the wondrous neem tree,
Azadirachta indica,
which featured earlier as the antidote to noxious tamarind. The neem grows to 20 meters or more, with evergreen, roughly ash-like leaves, much valued for their year-round shade. It is native to southern Asia, but its deep roots enable it to thrive in dry, poor soil. It has been planted and become naturalized throughout all tropical Asia, while the British took it to Africa in the early twentieth century to slow the spread of the Sahara. It has also been taken to Fiji, Mauritius, Saudi Arabia, and all tropical and subtropical America, including Florida, Arizona, and California. In the United States there are neem plantations.

There are many outstanding chemists among plants, but the neem is among the greatest of all. For centuries, indeed for thousands of years, the Indians have treasured the neem for medicines: it features in some of the most ancient Hindu texts. Many Hindus begin the new year by chewing neem leaves. Many clean their teeth with neem twigs. They treat skin disorders with its juice, and drink infusions as a tonic. Gum from the bark is used for dye. Neem has also proved active against more than two hundred species of insects, preventing them from feeding and inhibiting their reproduction—discouraging egg laying and disrupting the development of any eggs that are laid. As if to make the point, in 1959 a plague of locusts in India destroyed just about everything that grew, except the neems. The timber is termite-proof, and perfect therefore for hot climates, for everything from furniture to tool handles. Indians put the leaves in cupboards, to safeguard the contents. The leaves also make good fodder, while the seeds are 45 percent oil and provide excellent seedcake for livestock, or oil for lamps. Very properly, the neem is venerated. Many Indian place-names incorporate its name: Neemuch, Neemrana, Nemawar, and hundreds more. The neem is said to have been blessed with nectar, sent from heaven.

Science has reinforced the folk law. Different parts of the neem, but particularly the seeds, contain a host of potent organic compounds shown to be active against just about everything pestilential: bacteria, fungi, viruses, nematodes and mites, as well as insects. A powerful spermicide is in there too, raising hopes in some circles of an effective male contraceptive. Yet the extracts do not seem to harm mammals (including people) or birds. Outstanding among the compounds studied so far is azadirachtin. It is now being incorporated into commercial pesticides not only because it seems innately effective but also as part of a general swing away from industrial chemistry to biotech, based on natural processes and materials.

At this point, the story becomes less pleasant. In the 1990s U.S.-based companies began patenting various components of the neem, which the many excellent scientists of India had not bothered to do because, under Indian law, such medicinal, natural materials are not subject to patent. Thus the beneficent, sacred neem, rooted deep in Indian soil and Indian culture, has become the subject of squalid legalistic wrangling.