Wild coca plants are hard to distinguish from those used for cocaine

A new study published in the journal Molecular Biology and Evolution reveals that scientists struggle to reliably distinguish between different types of coca plants in South America despite the United Nations Office on Drugs and Crime‘s efforts to monitor coca cultivation and related deforestation for decades. 

Limitations around identification 

Typically, identification relies on leaf shape and size, but this method does not accurately differentiate between coca varieties used for cocaine extraction, traditional purposes, and wild-growing plants.

“To monitor the changing landscape of coca plantations, the United Nations Office on Drugs and Crime collects annual data on their areas of cultivation,” wrote the study authors. 

“However, attempts to delineate areas in which different varieties are grown have failed due to limitations around identification.”

Coca plants and the rising demand for cocaine 

Coca has been a crucial crop for Andean and Amazonian communities for at least 8,000 years and remains vital for millions of South Americans today. 

Its leaves, rich in active compounds, are used for cultural rituals, medicinal treatments, nutritional supplements, and as an everyday stimulant. 

However, in recent decades, global demand for cocaine has driven intensive coca agriculture, placing it at the center of armed conflict and deforestation.

Origins of coca plants 

Coca plants belong to the diverse genus Erythroxylum, which includes over 270 species, primarily native to the American tropics. 

Two main cultivated coca species are Erythroxylum coca (Huánuco coca) and Erythroxylum novogranatense. The former is native to wet mountain forests in Peru and Bolivia, while the latter is found in the dry valleys of the Cordilleras and the Sierra Nevada de Santa Marta. Traditional use of these plants includes flavoring and stimulant additives, such as for Coca Cola.

Inadequate classification system 

Researchers used statistical methods to analyze 1,163 leaf outlines from 342 digital herbarium specimens of wild and cultivated coca, finding significant overlap between species and varieties. 

This overlap likely leads to field misidentifications and highlights the need for diverse plant classification sources. 

An inadequate classification system can impede the identification of new varieties, crucial for both cocaine extraction and alternative uses like food supplements, fibers, or pigments.

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

“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.”

Genetic relationships between coca plants 

In addition to leaf shape and size, the researchers explored genetic relationships between coca plants, comparing these findings with existing taxonomic classifications. 

The experts assessed how well leaf traits matched genetic data and estimated when different coca species and varieties originated. 

The results indicated that distinct coca plants began evolving long before humans arrived in South America, though the timeline for the emergence of cultivated, cocaine-yielding coca remains uncertain.

While leaf characteristics were found to be unreliable for identification, the study emphasizes the potential of genetic techniques for more accurate identification and monitoring of coca populations.

Developing sustainable bioprospecting programs

“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,” said Oscar Alejandro Pérez-Escobar of the Royal Botanic Gardens at Kew, another co-author of the paper. 

“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.”

This study provides a new understanding of coca plant classification, which is essential for conservation, sustainable use, and reducing the plant’s association with recreational drug use, thereby highlighting its beneficial uses.

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