Date palm
The date palm, probably first domesticated in Mesopotamia, is the Babylonian and Assyrian Tree of Life and one of the first fruit trees to be domesticated in the Old World. The date palm is a multipurpose species whose range extends in a broad band through Saharan Africa, the Arabian Peninsula and southern Iran into Pakistan and north-west India. However, humans have moved dates extensively within this region, making it difficult to be specific about the species’ native range.
The palm’s fruits are rich in sugar, its trunks are used for timber, its leaves for roofing and basketry, whilst bark fibres are used in ropemaking. Moreover, artificial selection by people across the distribution has produced hundreds of varieties of date palm with many different uses. Two of the most familiar dates are Moroccan Medjool and Algerian Deglet Nour. In 2018, at least 8.7 million tonnes of dates were harvested, of which the three largest global producers were Egypt, Saudi Arabia and Iran.
As a stereotypical palm, slender, cylindrical trunks, which may be as much as 20 metres tall, are surmounted by a rosette of leathery, feather-like leaves, each of which may be up to six metres long. The palm’s early domesticators gradually learnt it was particularly fruitful when the leaves were in desert heat and its roots in wet mud. Thick-fleshed, domesticated date palms appear to have been selected from wild sorts with small, thin-fleshed fruits.
Date palm domesticators discovered that there are female and male plants; only females produce fruit, but males are essential for fruit production. Whilst in wild sorts sexual reproduction is the norm, Mesopotamians learned how to propagate the domesticated date from cuttings, creating orchards of female or male palms. Importantly, people discovered hand pollination; a few male palms could be used to produce reliable crops. Detailed palm pollination laws were established, with male palm flowers becoming articles of commerce.
In the late-nineteenth century, the anthropologist Edward Tylor drew attention to Assyrian bas-reliefs, such as those in the palace of the ninth-century BCE King Ashurnasirpal II at Nimrud, in present-day Iraq, where winged figures present cone-like structures to palm-like trees. Tylor interpreted the structures as bunches of male flowers of the date palm. It is tantalising that ancient Near Eastern images may depict plants as sexual organisms, whose reproduction could be manipulated by people. Ideas that were rejected in western plant sciences until the early eighteenth century.
Further reading
Porter BN 1993. Sacred trees, date palms, and the royal persona of Ashurnasirpal II. Journal of Near Eastern Studies 52: 129-139.
Taiz L and Taiz L 2017. The discovery and denial of sex in plants. Oxford University Press.
Zohary D et al. 2013. Domestication of plants in the Old World. Oxford University Press, pp. 131-134.
Stephen Harris