The avocado tree (Persea americana) is a medium-sized evergreen tree in the laurel family (Lauraceae). It is native to the Americas and was first domesticated by Mesoamerican tribes over 5,000 years ago. Then as now, it was prized for its large, extraordinarily oily fruit. The tree is likely native to the highlands connecting south-central Mexico and Guatemala. Sometimes called alligator or avocado, its fruit is botanically a large berry containing a single large seed. Avocado trees are partially self-pollinating and are often propagated by grafting to maintain consistent fruit set. Avocados are currently grown in many countries with tropical and Mediterranean climates. Mexico is the world’s leading avocado producer in 2020, supplying nearly 30% of the global crop this year. The fruits of the native varieties have a soft and buttery pulp, golden-green when ripe. Depending on the variety, avocados have green, brown, purple or black skin and can be pear, egg or spherical in shape. For commercial purposes, the fruits are harvested immature and ripen after harvest. The nutrient density and extremely high fat content of the avocado flesh make it useful in a variety of cuisines and it is often eaten to enrich vegetarian diets. Avocado trees produce one of the most resource-intensive crops in large-scale cultivation, and each avocado fruit requires 70 liters of water to grow. Although avocado tree C3 photosynthesis uses atmospheric carbon dioxide to create the fruit, the industrial scale at which the trees are grown still makes avocado production a net carbon source, emitting more than 400 grams (218 litres) of CO2 per fruit grown. In large producing regions such as Chile, Mexico and California, the demand for water from avocado plantations puts severe pressure on local sources. Avocado production also carries other externalities, such as environmental justice, human rights concerns, deforestation, and partial control of its production by organized crime in Mexico. Global warming is expected to cause significant changes in areas suitable for growing avocados and put production sites under pressure from heatwaves and droughts.