Summary
The genus Citrus comprises c. 25 species distributed from north‐east India and China to Australia and New Caledonia. Citrus fruits today make up the most significant component of fruit‐growing in warm countries, and extracts from them provide not only a very large share of the juice industry but are also used in many consumer products. When the first of them were brought to Europe, two millennia ago, however, they were not even consumed – the fruits being used for scenting and moth‐proofing clothes. From the 16th century onwards, the affluent commissioned glasshouses for citrus trees, called ‘orangeries’. This led to a phase of ‘citrusmania’, and citrus tree growing became a status symbol. The particular properties of their berries, called hesperidia, have in turn, led to their cosmopolitan significance as fruit‐crops.