The Tree that Changedthe World in One Century

Richard Evans Schultes

I can assure you that on that 14th of June ( 1875) (when Mr. Wickham arrived at Kew m a hansomcab with his precious bags of seeds, not even thewildest imagmation could have contemplated itsresult....- Sir W. T. Thiselton-DyerKew Bulletm (1912/, p. 65

History is usually written in the context ofpolitical, social, or religious changes. Yet itmight well be written from the point of viewof the effects that plants have had on the de-velopment of mankind and civilization.

It is safe to say that no smgle species ofplant has, in the short space of 100 years, soutterly altered lifestyles around the globe asHevea brasihensis, a member of the spurgefamily, which today is the source of 98 per-cent of the world’s natural rubber. Stop for amoment and try to imagine life withoutrubber!The introduction of this Amazonian tree

from the wild and its domestication in the

19th century was the work of the British bo-tamcal gardens, especially the Royal BotanicGardens at Kew, and is unquestionably themost outstanding example of the value ofsuch institutions in bettering life on earth.

Rubber-yielding trees and vines grew inthe Old World, yet, curiously, no significant

A group of rubber tappers bringing m therr dailyharvest of latex from forest trees m the Amazo-man region of Colombia. R. E. Schultes photo.

use of their product had been made any-where in the Eastern Hemisphere. WhenColumbus arrived in the West Indies, henoted that the natives were playing a gamein which rubber balls were employed, butthe rubber for these balls came not fromHevea but from Castilla elastica, of the figfamily.As early as 1755, King John of Portugal

tried to foster a rubber industry in Belem doPara at the mouth of the Amazon River:rubber shoes were manufactured for exportto Portugal, but the quality was so poor thatthe industry did not prosper. The process ofvulcanization, which has made rubber theuseful product that it is now, had not yetbeen discovered.

After Goodyear discovered vulcanizationin the 1830s, rubber became a product withever-increasing uses in the industrializingnations, and demand for it increased at a ver-tiginous rate. The only source was the wildstands of Hevea - especially H. brasiliensis- hidden away in the dark corners of thevast Amazon forests. The demand for rubberin Europe and the United States rapidly be-came so great that production from foresttrees rose from 31 tons in 1827 to 2607 tonsin 1856. This dramatic increase was accom-

plished by the virtual enslavement of wholetribes of Indians. Tapping the trees in thejungles for four or five months a year, awayfrom their agricultural lands and sources of

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Natural distribution of Hevea andH. brasihensis.

nourishment, falling prey to tropical dis-eases and malnutrition, and often sufferingfrom exposure, mistreatment, torture, oreven assassination if they did not bring inenough rubber, they were being extermi-nated by this forest industry, directedprimarily by unscrupulous "rubber-barons"who resided in the cities of Manaos and

Iquitos, usually in sumptuous luxury.The modern age of rubber had its begin-

nings in 1876, a "rubber revolution" thatwas the consequence of an incredible seriesof sometimes fortuitous events.

Hevea became known to the scientific

community when in 1775 the Frenchbotanist J. B. C. F. Aublet described thegenus from material collected in FrenchGuiana. He not only described the genus andits first species, H. guianensis, but detailedthe native method of exploiting it for rubberand appended numerous ethnobotanical dataon the use of the seeds by the natives as food.Twenty-six years later, K. L. Willdenow, aGerman botanist, described a secondspecies, H. brasiliensis, from material col-lected at the mouth of the Amazon River.

Subsequent botanical exploration of theAmazon Valley - notably that carried out

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by the British botanist Richard Spruce -continued to add new species to the genus,which now comprises 10 species and threevarieties.

Not all of the species yield a latex capableof producing rubber: only H. guianensis,H. benthamiana, andH. brasihensis havesufficient caoutchouc to give a usable rub-ber ; and of these, H. brasiliensis supplies thebest product.When m 1823 a Scot, Charles Macintosh,

discovered that rubber would dissolve in

naphtha, it acquired many new uses, leadingto the establishment of factories in England,France, and the United States. These fac-tories failed, however, because the productstill became sticky in the heat and brittle inthe cold.

This problem was overcome in 1839 whena Bostonian, Charles Goodyear, discoveredvulcanization, a process that greatly alteredthe physical properties of rubber andchanged the history of the significance ofthis vegetal product and its effect on humanlife. It led immediately to new and hithertounexpected applications and a host of newindustries. It also sparked the "rubberboom" of the Amazon, then the only sourceof natural rubber: production from the SouthAmerican forests rapidly increased.

Exploitation of wild rubber is a difficultand frustratmg operation. The natives, livingduring the tapping season under such abom-inable conditions, produced a poor-qualityproduct. The latex was frequently ladenwith bark, dirt, and stones and adulteratedwith other rubbers, since often the tapperswere punished if they did not procure stipu-lated quotas. Furthermore, each individualhad to labor from dawn or predawn untilnearly noon to tap 100 or fewer trees in his

forest circuit, then return to his shack andbegin the long process of coagulating thelatex. Large balls of rubber were formed bypouring the latex little by little over a polethat was rotated in smoke rising from an in-verted funnel.The death knell for this primitive industry

was sounded when the era of scientificallymanaged plantation practices began in 1876,the year that rubber seeds were first germi-nated successfully in the Royal Botanic Gar-dens at Kew. The domestication of the rub-ber tree served civilization in two ways.First, it provided an abundance of high qual-ity rubber at low cost, without which manyof our great advances in industry, medicine,domestic appliances, and transportationwould have been impossible. Second, whenplantations finally came into full productionin the second decade of the 1900s, the forestindustry was all but obliterated, with the re-sult that thousands of native tappers wereliberated from the intolerable and inhuman

exploitation to which they had been sub-jected for nearly 100 years. And, undoubt-edly, whole tribes - e.g., the Witotos of thenorthwestern Amazon, a truly noble race ofIndians - were saved from virtual extinc-tion.

Domestication of the rubber tree occurredat the time the British were seeking newcrops for their tropical colonies. The intro-duction of the quinine-bark tree into Indiafrom the Andes had just been highly success-ful. Sir Clements Markham, who had di-rected the introduction of that tree, wasconvinced that the rubber tree could be de-

veloped as a plantation crop that would be agood substitute for the coffee crop, which afungal disease had almost exterminated inAsia. He had Mr. James Collins prepare a

summary of what was then known about

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Parts of Hevea brasiliensis, the rubber tree.

rubber. Collins wrote: "In 1870, I came tothe conclusion that it was necessary to do

for the caoutchouc-producing tree what hadalready been done with such happy resultsfor the cinchona (quinine) tree." Sir JosephHooker, director of Kew Gardens, knew ofSpruce’s discoveries and studies of Hevea in

the Amazon, and he fully supported Mark-ham’s view concerning the future of Heveacultivation.

Several earlier attempts had been made tointroduce Hevea seed from Brazil, in 1873and 1875. None were successful. Hevea

seed, its latex rich in sugars, quickly fer-ments in the heat of the tropics, and the em-bryo is killed. But success eventually came.

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Seeds ofHevea brasiliensis. R. E. Schultes photo.

An Englishman, Henry Wickham, whohad spent many years living near the Ama-zon and Orinoco and who in 18 72 had pub-lished a book on his travels in tropical SouthAmerica, had previously sent seeds of Heveato Kew with no success. Fully realizing thatearlier shipments had failed because of slow

transport, Wickham resolved somehow tosurmount this difficulty. Then a fortuitousevent happened! In 1876 a steamboat fromEngland had sailed up the Amazon ladenwith cargo; it found no return load. "I de-

termined," Wickham wrote, "to plunge forit. I had no cash on hand. The seed was eventhen beginning to ripen. I knew that Capt.Murry must be in a fix, so I wrote chartering

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the ship." Wickham sent out his Indians tocollect the seed and pack it properly mwicker baskets. The ship raced downstreamfrom Santarem, 400 miles up the Amazon,and called in at customs in Belem at theriver’s mouth. Customs officials, told of thedelicacy of the plants "for delivery to HerBritannic Majesty’s own Royal Botanic Gar-dens of Kew," immediately, and with intel-ligence unusual among bureaucraticofficials, dispatched the ship, which steamedoff to England.

All of the earlier shipments had been senton sailing vessels. The few days saved byusing a steamboat ensured successful ger-mination in Kew’s hothouses. Of the 70,000seeds, 2800 germinated - a rate of 4 percent,astonishingly high for Hevea, even in thefield.

Young trees from this introduction weresent to Ceylon, where several of the originaltrees still are living in botanical gardens.From Ceylon some went to Singapore andother parts of the empire in the tropics. Thedomestication of this tree, which has in one

century so drastically changed life aroundthe world, would not have been possiblewithout a chain of botanical gardens and afar-sighted director at Kew like Hooker.

In Brazil stories are rife concerning theBritish "seed steal." At that time Brazilianlaw permitted the exportation of seeds, andcollection and exportation were carried outopenly. Many Brazilians are persuaded to be-lieve that rubber seeds were "stolen" or

"smuggled" out of the country, however,

The oldest tree of Hevea brasihensis in Malaysia,from one of nine seeds planted in 1877. Photo-graph courtesy of Rubber Research Institute ofMalaysia, Kuala Lumpur.

Henry Nicholas Ridley examining one ot his earlyexperiments in tapping systems of Heveabrasihensis, Malaysia. Photograph courtesy ofRubber Research Institute of Malaysia, KualaLumpur.

and fail to realize that Brazil’s major agricul-tural industries are based on plants intro-duced from foreign countries: coffee (origi-nally from Abyssinia), rice (from India),sugar (from Southeast Asia), soybeans (fromChina), jute (from India), cacao (from Co-lombia and Ecuador). In fact, most of theworld’s principal plantation crops are pro-duced in regions far from their originalhomes.When the Brazilians realized that the

British plantation efforts were to be success-ful, they prohibited further exportation of

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Trunk of Hevea brasihensis with hypertrophiedgrowth due to former tapping mth machadmho("httle ax") m the Amazon of Brazil. P. Alvimphoto.

rubber seeds, and that prohibition held untilvery recently. Consequently, the vast rubberplantation system of the Old World wasbased primarily on these original seeds,which were collected from a single localityand from a single (and not the most promis-ing) ecotype of Hevea brasiliensis. It is be-lieved that the 70,000 seeds came from 26original trees. In view of this, the enormousimprovement m the commercial rubber treein the space of 100 years seems incredible.The earliest plantation set out in Ceylonyielded 400-450 pounds of dry rubber peracre per year; there are new clones of the

rubber tree that now yield more than 3000pounds, and, with a recently developedchemical treatment of the bark, some clonesmay almost double that amount.

Many names of major importance areconnected with the historical accomplish-ment of domesticating a wild tree of thehumid Amazon. These include Aublet,Spruce, Macintosh, Goodyear, and Wick-ham, mentioned earlier. But Wickham andtwo others - Ridley and Cramer - wereperhaps all-important in the creation of thegreat plantation industry that supplies theworld with more than 98 percent of itsnatural rubbers. Wickham, who lived to avenerable old age, was rightfully knighted inthe late 1920s for his part in the creation ofthe rubber industry.Henry N. Ridley was appomted director of

the Botanic Gardens in Singapore in 1888. Itwas my unexpected good fortune in 1950 tospend several days chatting with Ridley inhis 95th year. He lived near Kew Gardensand was overjoyed to review some of hishopes, his trials, his successes in the earlyhistory of rubber in the Far East with ayoung botanist who was studying the nu-merous species and their ecotypes in thewild in South America. It was during thesepersonal exchanges that I reahzed that Rid-ley was in fact one of the major founders ofour modern rubber plantation industry.When Ridley took up his position, he

found only nine original trees and some 1000young plants left from the original introduc-tions to the Malay Straits in 1877. He im-mediately raised 8000 more plants from seedimported from Ceylon. These trees, from theoriginal Wickham stock, became the mothertrees of much of the rubber that eventuallycovered a large portion of Malaya.Next Ridley began his celebrated experi-

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Pieter J. S. Cramer (left). The identity of the otherman is unknown. The tree is one of the originalWickham trees in the Botanical Garden, Ceylon.Photograph courtesy of Dr. O. S. Pires, RubberResearch Institute of Srt Lanka, Agalwatta, SmLanka.

ments on tapping methods. At that timetrees in the Amazon were slashed accordingto a great variety of makeshift techniques,frequently to the detriment of the tree. Themost prevalent method mvolved the use ofthe "machadmho" - a small ax used tomake deep incisions in vertical lines up anddown the trunk, causmg eventually enor-mous hypertrophied tumors, which laterprevented efficient tapping.

Ridley tried cuttmg off very thin layers ofthe bark with a sharp knife in a sloping

channel, avoiding injury to the cambium,since in Hevea all of the latex-bearing ves-sels are external to the cambium. He beganwith the well-known herring-bone methodand recommended infrequent tapping toallow the trees to rest. Eventually, helearned that more frequent tappings wouldnot harm the tree and abandoned the

herring-bone system and cut in slopes fromright to left, since cuts in this direction wereshown to give higher yields. Among numer-ous other discoveries, he experimentallyshowed the advantages of tapping done inthe morning rather than the afternoon.

Ridley’s advances, perhaps more than anyother, assured success of the Asiatic planta-tion mdustry. By 1897 all tapping in Asiawas based on Ridley’s scheme of reopeningthe wound. The sudden increase in worlddemand for rubber further stimulated re-search into efficient and higher-yielding tap-ping techniques, in all aspects of which Rid-ley took part. His experiments led even-tually to the spiral system of tapping, whichtoday is nearly universal in plantation prac-tice.

Ridley made another significant contribu-tion to the rubber mdustry of the future inhis campaign to establish rubber as a planta-tion crop. A series of events led him to this:a serious fall in the world price of tea, thedevastating fungal disease of Coffea arabica,and poor results with cacao. Another factorwas the increasing use of the automobile;automobile tires gradually became thegreatest smgle consumer of the product. Rid-ley seized the opportunity, and soon planterswere establishing rubber.Again it was my good fortune in 1950,

when Dr. P. J. S. Cramer was retired inUtrecht, Holland, to spend three days chat-ting with oude Piet ("old Pete"), as the uni-

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versity students affectionately called him.We reviewed the initial introduction ofHevea stock to the Dutch East Indies fromthe British Malay Straits - material derivedfrom the original Wickham seeds - and hisearly successful efforts to introduce fromSouth America seeds of several other speciesof Hevea for eventual genetic studies. Hetold me about the difficulties he experiencedin attempting to convince commercial de-velopers that the planting of seeds (instead ofusing clonal material) was not the best wayof establishing plantations of rubber trees. Inthese three days we experienced a remark-able camaraderie based on our very divergentexperiences with Hevea, and I acquired anabiding understanding of the difficulties en-countered by these pioneers: Ridley andCramer.

When the Dutch had established a planta-tion crop from material originating inPenang, Malaysia, Cramer carried out thefirst variation analyses on Hevea brasilien-sis. These early studies indicated that thespecies is extremely variable, especially withrespect to yield of latex, an important com-mercial consideration. Through his analysesCramer demonstrated the impossibility ofpredicting yield of rubber from plantationsestablished on seed material, mainly be-cause of cross pollination. He predicted thatvegetative selection, cloning, and generativeselection or breeding would lead to im-provements in yield. All his predictionsproved true. Cramer’s studies led to theeventual vegetative reproduction of high-yielding, clones, which today is basic to allrubber-plantation practice.

Letter to the author from Henry N. Ridley m his95th year.

Plaque commemorating Sir Henry Wickham’ssuccessful introduction of seeds of Heveabrasihensis from the Amazon m 1876. Photo-

graph courtesy of the Rubber Research Instituteof Malaysia, Kuala Lumpur.

Later, in 1918, Cramer patented a methodof marketing budwood from high-yieldcloned trees, which ad infinitum would pro-vide the basis of plantation material. He alsoinvented the Testatex knife, patented in1931. This knife has a vertical series of

V-shaped blades, and when pressed into thestem or trunk of young nursery plants mea-sured the length of the "drip" of the exudinglatex, thereby indicating yield potential longbefore the trees matured at seven years.The famous Colombian author Jose Eu-

stacio Rivera wrote one of the great novels of

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A modem plantation of Hevea brasiliensis inMalaysia. Photograph courtesy of Rubber Re-search Institute of Malaysia, Kuala Lumpur.

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Latin America on life on the Amazon duringthe rubber boom. The title, La Voragine (TheVortex), refers to the belief that the junglemysteriously swallows up the rubber tap-pers. One magnificent passage describes thealmost fearful worship of the rubber tree inthose days: "I have been a rubber tapper. Iam a rubber tapper. I have lived in the

muddy swamps in the solitude of the forestswith my crew of malaria-ridden men cuttingthe bark of the trees that have white bloodlike that of the gods." "

If we consider the changes for the goodof mankind that "white blood" broughtabout when the rubber tree was finallydomesticated, perhaps we might agree that itwas actually blood of the gods!

Selected ReadingsBangham, W. N. 1945. "Rubber Returns to Latin Amer-

ica." InNew Crops for the New World, edited byC. M. Wilson. New York: Macmillan.

Barlow, C. 1978. The Natural Rubber Industry.Selangor, Malaysia: Oxford University Press.

Collier, R. 1968. The Rmer that God Forgot. London:Collins.

Dijkman, M. J. 1951. Hevea: Thirty Years of Researchm the Far East. Coral Gables, Florida: Universityof Miami Press.

Drabble, J. H. 1973. Rubber in Malaya 1876-1922: TheGenesis of the Industry. Kuala Lumpur,Malaysia: Oxford University Press.

Hardenburg, W. E. 1912. The Putumayo: The Dev~l’sParadise. London: T. Fisher Unwm.

Polhamus, L. G. 1962. Rubber: Botany, Production andUtW zation. New York: Interscience Pubhshers.

Schultes, R. E. 1977a. "Wild Hevea: An UntappedSource of Germ Plasm." Joumal of the RubberResearch Institute of Sm Lanka, 54: 227-57.. 1977b. "The Odyssey of the Cultivated Rubber

Tree." Endeavour (New Series) 1 (314~: 133-38.. 1970. "The History of Taxonomic Studies m

Hevea."Regnum Vegetabile, 71: 229-93.Singleton-Gates, P., and M. Girodias. 1959. The Black

Diames of Roger Casement. New York: GrovePress.

Wilson, C. M. 1943. Trees and Test Tubes : The Story ofRubber New York: Henry Holt.

Woodroffe, J. F., and H. H. Smith. 1915. The Rubber In-dustry of the Amazon and How Its SupremacyCan Be Maintained. London: John Bale, Sons,and Danilson.

Wycherley, P. R. 1968. "Introduction of Hevea to theOrient." The Planter (Kuala Lumpur), 44: 127-37.

Richard E. Schultes is jef frey professor of biology and ddirector of the Botanical Museum of Harvard Umver-sity.