Systematics and Evolution of the Genus Phoenix: Towards Understanding Date Palm Origins

The date palm (Phoenix dactylifera L.) is an iconic crop of hot and arid regions of North Africa, the Middle East and up to northwestern India. It is a member of the genus Phoenix that constitutes a monophyletic group within the Coryphoideae subfamily, in the palm family. The genus Phoenix is composed of around 14 species whose native distribution is across the South of Europe, throughout Africa, the Arabian Peninsula and South Asia. Species boundaries and relationships are poorly understood owing to the morphological similarities between the species and their ability to hybridise. In this chapter, we review the past and present distribution of Phoenix species and aspects of their reproductive biology and genome dynamics. We then summarise the current state of knowledge of the taxonomy and phylogeny of Phoenix and we outline the main challenges that have so far limited our understanding of the genus’ systematics and evolution. We conclude with a roadmap to address these challenges by combining the extraordinary resource of specimens stored in herbarium collections and the power of high throughput DNA sequencing technologies.