PLoS ONE 11, e0152394 (2016)

Date palm (Phoenix dactylifera L.) is one of 14 barely distinguishable species in the genus, meaning that determining how, when and where it was domesticated is very difficult. Muriel Gros-Balthazard of the University of Montpellier, France, and colleagues have solved this problem with a morphometric analysis of 1,625 Phoenix seeds from different species.

Credit: © SARAH IVORRA/ISEM

P. dactylifera is economically important in the Middle East and North Africa, not only for the fruit it produces but also because the trees shelter other crops. Moreover, there are no confirmed wild populations of P. dactylifera still living, meaning that archaeobotanists, who rely on modern reference species to characterize archaeological specimens, are not even sure what the wild precursor to modern date palms would look like.

The new method allowed Gros-Balthazard et al. to differentiate between Phoenix species and define their unique characteristics. In particular they found that cultivated date palm seeds are distinctively longer and more elongated in shape than wild species. They used this domestication hallmark to suggest that some uncultivated date palms in Oman, previously thought to be feral, are actually wild. The authors intend to roll out the method for identification of seeds recovered from archaeological sites, such as Miri Qalat and Shahi Tump in Pakistan, to further illuminate the domestication of this key species.