The date palm with blue dates Phoenix senegalensis André (Arecaceae): A horticultural enigma is solved

• We determine the origins and relationships of the Phoenix date palm with bluish dates.
• Phoenix senegalensis André is a variety of Phoenix canariensis with bluish dates.
• Phoenix senegalensis André is P. canariensis “Porphyrocarpa”.
• Phoenix canariensis “Porphyrocarpa” is useful for ornamental horticulture.
• Molecular markers and morphology link Phoenix senegalensis with P. canariensis.

This study aimed to determine the status, origins and relationships of the Phoenix date palm with bluish dates, which is cultivated in gardens and parks and known as Phoenix senegalensis or P. canariensis “Porphyrocarpa”, with other Phoenix species.On one hand, a total of 98 descriptive characters and 398 states related with ecological preferences, phenology and plant morphology, were used to assess the relationships among 11 samples of P. senegalensis from Spain, France, Italy and Portugal with 61 samples that represent ten Phoenix species: P. reclinata, P. pusilla, P. caespitosa, P. sylvestris, P. atlantica, P. theophrasti, P. iberica, P. abyssinica, P. canariensis and P. dactylifera. Also, some hybrids were included such as P. sylvestris × P. dactylifera, P. canariensis × P. dactylifera, P. reclinata × P. dactylifera and P. canariensis × P. reclinata.On the other hand, the genetic relationship was evaluated comparing eight microsatellite loci of 7 samples of P. senegalensis from Spain, France, Italy and Portugal with 308 specimens of P. canariensis, collected from natural populations of five different islands of the Canarian archipelago, together with 40 individuals of P. dactylifera collected from different cultivars of Marrakech (Morocco).Considering the analyzed evidences, the date palms with bluish red fruits traditionally called as P. senegalensis, which is cultivated in gardens of Europe at least from the nineteenth century, is considered part of the variability of P. canariensis H. Wildpret which is useful for ornamental horticulture.

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