A DNA test has confirmed Meru miraa is unique to the region and genetically different from its relatives cultivated in other parts of the world.
This, as local scientists have argued, suggests Meru's miraa should be judged individually and not lumped together with others, which are of different genetic or chemical make-up.
The study involved the National Museums of Kenya and researchers from the US Department of Agriculture, Portugal, Austria, Ethiopia, Saudi Arabia and Yemen.
The DNA results reinforce the case by Kenya government scientists who recently declared miraa safe for human consumption.
In a study that has since turned controversial, researchers at the Kenya Medical Research Institute (Kemri) in February confirmed chewing of Meru or Embu miraa had no ill effects on humans.
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During their presentation at Kemri’s annual scientific conference, they had argued that Meru and Embu miraa had its own identity and should not be lumped together with others for condemnation.
“A plant growing in different geographical locations never contains the same chemical constituents, it is therefore incorrect to assume that miraa grown elsewhere would be similar to our own in terms of effects and toxicity,” said the Kemri report.
Local scientists argued that the miraa export ban in Europe was based on studies done elsewhere with no bearing on the Meru crop.
While the DNA study had nothing to do with the Kenya controversy or the chemical composition of the plant, it however confirms that the Meru miraa originated from the area and is hardly grown anywhere outside the country.
An advance copy of the report, courtesy of study leader Prof Mark Williams of Colorado State University, US and the United States Department of Agriculture, states that the team was testing three theories on the origin and dispersal of cultivated miraa.
The first argues that cultivated miraa originated in Yemen moving to Ethiopia and then Kenya. The second hypothesis runs that cultivated miraa first originated from Ethiopia and then spread to both Yemen and Kenya.
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The third, and the theory which seems to have won the day, argues that miraa cultivation had an independent origin in Kenya distinct from that in Ethiopia and Yemen.
The team had collected 1,561 leaf specimens of both wild and cultivated miraa leaves from Kenya, Ethiopia, Yemen, Madagascar, Tanzania, Malawi, Zimbabwe, and South Africa and analysed their genetic composition.
Ethiopian species were found to be the most dispersed for cultivation globally, including in Yemen and parts of Marsabit in Kenya.
“We did not identify any cultivated genotypes translocated from Kenya to the other countries we sampled,” says the report.
The report to be published this week in the American Journal of Botany, suggests miraa grown in the Meru/Mt Kenya region has largely remained virgin.