Cocas
The best-known species in the genus Erythroxylum is coca (Erythroxylum coca). This species’ leaves have been chewed and brewed by indigenous South Americans for thousands of years. As a source of minor nutrients, a stimulant and an appetite suppressant, coca united the Incan empire across the Andes. Coca’s specific name is derived from its indigenous Quechan name, kúka.
Sixteenth-century Spanish physician Nicolás Monardes introduced Europeans to coca’s properties. In the 1830s, the South American travel writings of German naturalist Eduard Poeppig focused Europeans on coca’s cultural and medicinal importance– albeit some people regarded these reports as mere travellers’ tales.
In 1855 an anaesthetic alkaloid (cocaine) was isolated from coca leaves. Coca had begun a new chapter in its long history. The end of the nineteenth century saw the discovery of methods for the purification and synthesis of cocaine. Medicinally, cocaine was used in dental and ophthalmic surgery. Coca-leaf extracts were included as stimulants and anaesthetics in alcoholic tonic wines, pep pills and patent medicines and as soft-drink flavourings. By the end of the twentieth century, use and possession of cocaine was illegal in many countries.
Throughout its native range, people have selected numerous coca varieties for different uses, and for optimal growth across diverse environments. For example, coca plants are usually propagated by seed, but the variety grown in Amazonia is propagated as cuttings – consequently, entire coca plantations are genetically identical.
There are approximately 250 species of trees and shrubs in the genus Erythroxylum, distributed through the world’s subtropical and tropical regions; the centres of species diversity are in South America and Madagascar. Many of these species look very different to coca. For example, Erythroxylum species found in periodically dry savannas often have thick, corky bark and underground stems to protect growing buds from periodic fires.
Four hundred weeks ago, the Plants400 project began with yew, a tree grown by the first keeper of the Oxford Physic Garden as an ornamental; its past use had been in warfare and future use would be in medicine. In this closing entry, coca is unlikely to be found growing in European gardens. However, it was an important element of Andean cultures long before it became part of western medicine and warfare, and a global addiction and political, economic and social destabiliser. Both yew and coca emphasise the dynamic, changeable nature of human relationships with plants – relationships that vary with time, space and people.
Hobhouse, H 1999. Seeds of change. Six plants that transformed mankind. Papermac, pp. 293-363.
Schultes, RE and Raffauf, RF 1990. The healing forest. Medicinal and toxic plants of the northwest Amazonia. Dioscorides Press, pp. 166-176.
Stephen Harris