Cacao Tree

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This eighteenth-century depiction of cacao pods shows how each fruit is packed with sweet pulp enclosing the much sought-after beans. Photo by The Board of Trustees of the Royal Botanic Gardens, Kew


Theobroma cacao  

Every chocolate-lover owes a deep debt of gratitude to the unassuming tropical tree species, Theobroma cacao, but also to the ancient peoples who first discovered its delights. The cacao tree from which chocolate is made was expertly cultivated by the ancient Maya and Aztec peoples of Central America, but recent research suggests that its first use dates back to much earlier societies living in South America, in Ecuador, over 5,000 years ago. Studies of ceramics of the Mayo-Chinchipe culture show cacao was being consumed there, most probably as a drink. It’s now thought that its popularity spread, through trade, up into Central America over hundreds of years. The Mayan name for the plant was kakaw or kakawa—which has become cacao—now both its scientific species name and its common name. It was eighteenth-century taxonomist and chocolate-lover Carl Linnaeus who gave the genus its name Theobroma—meaning “food of the gods.” Cacao is a member of the Malvaceae or mallow family and is related to hibiscus and okra. Believed to have originated in the rainforests of the Amazon, cacao is a small tree that grows up to 8 meters (26 feet) tall. It needs a tropical climate, but also shade and high humidity, preferring to grow in the understory of the rainforest. As a crop it therefore has to be cultivated under taller trees. Today, these include other crops such as bananas (Musa) or rubber (Hevea brasiliensis), giving added benefi t to the farmer. Cacao produces surprisingly small and delicate-looking pink flowers directly from its trunks (a feature known as cauliflory) throughout the year. Once these are pollinated by a species of midge, the large pods develop. These yellow or red, ridged oval fruits (technically berries) grow up to 25 centimeters (10 inches) long, and are filled with a sweet white pulp that holds thirty to forty seeds or “beans.” In a good year, a healthy tree can produce around thirty such pods.

Cacao pods, and the beans they contain, were once so important and desirable they were even used as currency. Photo by The Board of Trustees of the Royal Botanic Gardens, Kew

The Maya were well practiced in how to grow cacao in the forest, and how to ferment, toast, dry and grind the beans to make a paste. This was then mixed with hot water and poured from a height from one vessel into another to produce a foaming drink. Later, the Aztec people also treasured the cacao tree, believing it to be a gift from the gods, as its current scientific name reflects. The Aztecs are thought to have preferred their version of the drink cold, and prepared it using high value implements, reputedly drinking it from golden cups. This was a truly special drink — only for the elite of their society and for warriors. Commoners, women and children were not allowed even to taste it. The beans were precious and highly prized: they were traded widely and even used as a form of currency. Cacao was also offered in both tribute and as a sacrifice. Moctezuma (Montezuma) II — the ruler of Tenochtitlan (modern Mexico City) between 1502 and 1520, was recorded as drinking many flavored versions of the foaming dark drink they called cachuatl. Vanilla, chilli, spices, honey and herbs or flowers were all used to spice up his chocolate drink, to which he seems to have been slightly addicted.

Brought back to Europe by the Spaniards around 1544, cacao soon became a novel drink at the Spanish court. It was then introduced throughout Europe in the sixteenth century, and was originally taken as a medicinal drink to aid digestion and to settle the stomach. It was when it was once more mixed with hot water, as the Maya had done, that the name “chocolate” was born and this drink grew in popularity. It was much favored by French royalty at Versailles — Louis XV reputedly had his own recipe. In the seventeenth century chocolate houses, like today’s coffee shops, sprang up in Oxford and London. Samuel Pepys recorded in the 1660s that he often enjoyed a morning drink of “chocolatte.”

The Economic Botany Collection at the Royal Botanic Gardens, Kew, holds a wealth of plant products, including these rolls of pure cacao from Trindad and Tobago. Photo by The Board of Trustees of the Royal Botanic Gardens, Kew

Another important development in our love affair with chocolate came after Sir Hans Sloane visited Jamaica and was distinctly unimpressed by the Central American way of drinking chocolate, considering it “fit only for swine.” He then devised a recipe using hot milk and sugar that made it immensely more palatable and desirable. Chocolate grinding and making began to become an industry across Europe in the eighteenth century and in 1828 the Dutchman Coenraad van Houten invented a process that created cocoa powder and also facilitated the creation of solid chocolate. By 1842 Cadbury brothers were in business in the UK selling powdered and solid chocolate made from cocoa butter and ground beans, but it remained a luxury item until the mid-nineteenth century when import levies were lifted. Swiss chocolatiers also began to create new and wonderful confections, and demand and production took off.

Always thought to be delicious and desirable, dark chocolate and pure cacao are now known also to have real health benefits. Cacao contains phenols and flavonoids which have antioxidant effects thought to inhibit cancer and cardiovascular disease. Cacao also contains theobromine and caffeine alkaloids. It is these that are believed to improve mental alertness and can have an addictive effect.

A fruiting cacao tree, ready for harvesting. The small flowers and large pods that follow pollination are produced direct from the trunk and branches. Photo by Wellcome Collection

Today, chocolate is enjoyed across the world in myriad forms and is generally sold at an affordable price. Over 4 million tonnes of beans are now produced each year and it is predicted that demand will soon outstrip supply. Although native to tropical America, today most cacao is grown in West Africa – with the Ivory Coast and Ghana being the top producers. It is an extremely important crop for around 5–6 million small farmers across the tropics.

But there is a potential threat to the security of our much-loved chocolate crop. Unfortunately, Theobroma cacao has limited genetic variability and seems to have little natural resistance to pests and diseases. Plantations are plagued by problems including fungi such as frosty pod rot and witches’ broom in the Americas, swollen shoot virus in Africa, and cocoa pod borer in Southeast Asia. Along with climate change and the poverty of the regions in which cacao is often grown, and with so many people depending on it for their livelihoods, the stakes are high. However, many scientists are working together to find solutions to save the cacao tree. In 2010 the DNA of the highly prized ancient Maya variety ‘Criollo’ was fully sequenced, allowing researchers to discover the genes responsible for protecting the plant against disease and so help breed hardier trees. Conserving the wild relatives of T. cacao in their natural habitat may also offer valuable genes to safeguard the future of our favourite sweet treat, another very good reason to support the protection of the rainforests.

More from Remarkable Trees:

Cover courtesy of University of Chicago Press

Reprinted with permission from Remarkable Trees by Christina Harrison and Tony Kirkham published by The University of Chicago Press. © 2019 Thames & Hudson Ltd and the Board of Trustees of the Royal Botanic Gardens, Kew All rights reserved.

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