Experts can’t tell apart wild and cultivated coca plants

By Stephen Beech via SWNS

Even experts can't tell wild coca plants from those grown to make cocaine, according to a new study.

Researchers found that while the United Nations Office on Drugs and Crime has collected annual data on areas of coca cultivation in South America for decades to monitor illegal plantations and deforestation, scientists can’t reliably distinguish between different types of coca plants.

They say that while identification often relies on leaf shape and size, it doesn't reflect differences between coca varieties grown for extracting the alkaloid cocaine - the active ingredient in the recreational drug, coca cultivated for traditional purposes, and wild-growing coca plants.

South American coca has been a "keystone" crop for many Andean and Amazonian communities for at least 8,000 years, and it still plays a vital role in the livelihoods of millions of South Americans today.

People use its leaves, rich in active compounds, for cultural rituals, medicinal treatments, nutritional supplements, and as an everyday stimulant.

But over the last half-century, global demand for alkaloid cocaine, through industrial levels of extraction of the single compound, has driven intensive agriculture of the plant and placed it at the center of armed conflict and deforestation.

Coca belongs to the genus Erythroxylum, which comprises more than 270 different species, many native to the American tropics.

Among those, two species of cultivated cocas are found in mostly distinct regions of northwestern South America.

The most widely cultivated is Erythroxylum coca (Huánuco coca). Its coca variety is native to wet mountain forests of the eastern Andean slopes of Peru and Bolivia, and its ipadu variety in the Amazonian region.

The less widely cultivated Erythroxylum novogranatense has historically been grown in the dry valleys of the Cordilleras and the Sierra Nevada de Santa Marta.

Farmers cultivated its truxillense variety - known as 'Trujillo coca' - in arid parts of north-western Peru for traditional use and it is a flavoring and stimulant additive for Coca-Cola .

The leaves of the two species - plants grown specifically under human cultivation and adapted to a human environment -were thought to be different from leaves of closely related wild Erythroxylum species by being smaller, rounder and softer.

As for distinguishing between the two, leaves of E. coca are, in general, rounder than E. novogranatense.

That simple difference has been used in the field for coca plantation monitoring surveys, say scientists.

However, they found differences in leaf size and shape may not be a reliable way to separate the types of plants.

Despite extensive studies, the boundaries between cultivated coca varieties and their wild relatives are poorly defined.

The research team used 1,163 leaf outlines from 342 digital herbarium specimens of wild and cultivated coca to extract size and shape data.

Using statistical methods, they showed that there is a "high degree" of overlap between the species and their varieties, which has "almost certainly" led to misidentifications in the field.

The team says their findings, published in the journal Molecular Biology and Evolution , also highlight the importance of using diverse sources for plant classification.

Study co-author Fabio Andrés Ávila, of the New York Botanical Garden , said: “We are rethinking how to classify coca plants, both cultivated and wild, after adding new data about their leaves and genes.

“This is important for Colombia's biodiversity and for communities that use coca for traditional purposes, providing new information sources about the plants they depend on.”

The research also showed that distinct coca plants had begun to evolve long before humans first arrived in South America 15,000 years ago, though the timeline for when the cultivated, cocaine-yielding coca plants emerged remains uncertain.

While leaf shape and size revealed traits that are characteristic of cultivated cocas, namely being rounder overall and narrower at the base, the researchers found those characteristics "unreliable" for identification purposes.

The study highlights the potential of genetic techniques as a more precise method for identifying and monitoring coca.

Co-author Dr. Oscar Alejandro Pérez-Escobar, of the Royal Botanic Gardens at Kew, London, said: “One of the primary objectives of our research is to propose a stable classification system and a comprehensive genetic database.

"This will enable us to confidently identify the different populations, varieties and species of cultivated coca and their wild relatives."

He added: “Such a system is crucial for developing sustainable bioprospecting programs and the coca tree holds immense potential in this regard.

"But first, it is essential to separate the plant’s valuable attributes from its association with the recreational drug, reshaping its perception and highlighting its positive uses.”

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