The study of botany developed rapidly at this time, but there were many aspects of citrus that botanists and citrus collectors did not understand. Sudden changes in temperature, periods of drought, unusually high rainfall or even wind could trigger mutation. This often affects only one or two branches of a tree, which flower at a slightly different time, produce fruit that matures at a different rate, or is even an entirely different shape and colour from the fruit on the rest of the tree. When this happened to a tree in a citrus collection it was a wonderful mystery and, at this time of scientific exploration, it made citrus an even more fascinating and desirable collector’s item.

Montaigne, the French essayist and traveller, thought the villa at Castello ‘not worth looking at’ when he visited in 1581, but he was delighted by the garden. ‘In every direction, you see a variety of arbours,’ he reported, ‘thickly formed of every description of odiferous trees, cedars, cypresses, orange trees, lemon trees, and olive trees, the branches of which are so closely interwoven that the sun, at its meridian height, cannot penetrate them.’

TAGLIOLINI ALLE SCORZETTE DI ARANCIA E LIMONE

When I ate this pasta and tasted its surprising orange and lemon sauce for the first time, I was careful to ask which kinds of lemons were used in the recipe. I was in Settignano, a village high above Florence, where Damiano Miniera had founded a dynamic restaurant and wine bar called Enoteca la Sosta del Rossellino. Damiano was from Sicily, where lemons are a major crop, and yet he insisted that any variety of lemon would do for his tagliolini. He wasn’t jealous of his recipes and he would recite this one to anybody who could hear it on the crowded restaurant floor.

• 2 oranges
• 1 lemon
• a knob of butter
• ¼ onion, chopped
• a big splash of white wine
• 100ml single cream
• salt and freshly ground black pepper

Peel the fruit, being careful to exclude the pith. Cut the peel into razor-thin slivers and cook them in boiling water for 5 minutes or so to remove some of the bitterness, then drain them. – Melt the butter in a small frying pan and add the onion. When it’s translucent, pour in the white wine. Add the drained peel, together with the juice of the oranges and the lemon and the cream. – Simmer for 5 minutes before seasoning with salt and black pepper and and sloshing the sauce over a bowl of warm pasta.

Many of the familiar fruits cultivated today are the hybrid progeny of spontaneous cross-pollination between wild or cultivated citrus trees. For example, oranges (both sweet and sour) are hybrids between mandarin and pomelo, grapefruit is the result of a pomelo– orange cross and the lemon is a hybrid between citron and sour orange.

Today, citrus is an enormous genus with an incalculable and ever-expanding membership, and yet originally the citron, the pomelo and the mandarin were the only species of citrus in the world.

If you were to open a new restaurant here, the Mafia would be at your door immediately. ‘So you are opening a restaurant,’ they’d say. ‘What can we do to help?’ You would know that all the bread you needed in a week cost €70 and yet, if you agreed to allow them to supply it for €100, that would settle the pizzo.

A limonaia is often an impressive building. Take the lovely rococo Stanzone degli Agrumi in the Boboli Gardens in Florence, which was built for Pietro Leopoldo in 1777 and is large enough to overwinter 500 pots of citrus. The building stands on the site of the menagerie used by the Medici to keep exotic animals given to them as diplomatic gifts. The giraffe and hippopotamus, the elephant and dromedary were long gone, and an elegant, 100-metre-long limonaia designed by Zanobi del Rosso took the place of their old quarters.

I’ve often wandered through the sun-drenched, dusty spaces of a limonaia in summer and seen a sheet of paper nailed to the wall or weighted down with a brick. On it will be a sketch, sometimes a very rough one, of the position of each pot when it is brought indoors in the autumn. The trees become accustomed to the temperature and fall of light in these places, and by replacing them in exactly the same spot each year, the gardeners minimize the trauma of the transition from inside to out.

I was given a series of phone numbers for Antonio Miceli, one of the consortium’s directors. Miceli never seems to stay in one place for long. He’s a man in a hurry, with multiple businesses and not enough time to run them. When I eventually tracked him down he said, ‘The harvest is finished and the rabbis fly out tomorrow, but I can call you back next year.’ You can trust Antonio Miceli to do what he says, and a year later he called me back to say that the harvest would begin in a week.