The guava belongs to the Myrtaceae, the myrtle family, and so counts amongst its kin the clove, the allspice, and the eucalyptus; the common guava is Psidium guajava, a small, quick-growing tropical tree native to the warm Americas. Its range at the coming of the Europeans ran from southern Mexico and Central America through the islands of the Caribbean to the northern shoulder of South America, and across that whole region it had been gathered and grown for thousands of years; archaeological remains in coastal Peru carry its cultivation back well beyond two thousand years. The fruit is round or pear-shaped, its thin green or yellow skin enclosing a flesh that may be white, pink, or deep salmon-red, dotted with many small hard seeds, and carrying a heady, musky, sweet-sharp perfume that fills a room as it ripens. It is extraordinarily rich in vitamin C, several times that of an orange, and so quick and willing a grower that it runs wild and weedy wherever the climate suits, a pioneer of waste ground across the tropics.

Two relatives share the name and the family without being the same fruit. The strawberry guava (Psidium cattleyanum), a smaller, cherry-sized fruit of deep red or yellow with a strawberry-like tang, is native to the Brazilian coast and has become a notorious invader of Hawaii and the Mascarenes. The pineapple guava or feijoa (Acca sellowiana), a different genus altogether, is a fruit of the cool South American highlands of southern Brazil, Uruguay, and Argentina, its green egg-shaped fruit tasting of pineapple and mint; carried to New Zealand, it became there a national favourite. But it is the common guava that conquered the tropics. The fruit's great weakness is its perishability, for it bruises and ferments within days of ripening; its salvation, and the foundation of its global cuisine, was the discovery that it could be cooked down with sugar into a dense, sliceable paste that keeps for months, the goiabada and pasta de guayaba that carry the guava far beyond its short fresh season.

The guava was one of the New World's most portable gifts, for its seeds travel and germinate with ease, and the Spanish and Portuguese carried it with extraordinary speed across the whole tropical world in the sixteenth and seventeenth centuries. The Spanish took it west across the Pacific on the Manila galleon, the great treasure fleet that bound Acapulco to Manila, and from the Philippines the guava spread through maritime South-East Asia, into Siam, Vietnam, and the Indonesian and Malay world, where it was eaten green and crisp with salt and chilli and dropped into the souring pot. The Portuguese carried it the other way, around Africa to their Indian territory at Goa, and India took to the guava so completely that it is today the largest grower of the fruit on earth, the amrud eaten fresh from every roadside cart with a dusting of salt and chilli, and set, in the Portuguese-Goan manner, into the firm guava cheese called perad.

Wherever the fruit went, two traditions followed it. The first was the fresh fruit itself, eaten out of hand and, across South-East Asia, India, and Latin America alike, sharpened with salt, chilli, and lime against its musky sweetness. The second was the paste. The Iberians brought with them the old Mediterranean art of cooking quince into a solid, sliceable fruit cheese (the membrillo of Spain), and applied it to the guava with cane sugar, creating the goiabada of Brazil and the pasta de guayaba of the Hispanic Caribbean: dense blocks of dark, sweet, sliceable guava that, paired with a slice of fresh white cheese, became the beloved sweet known across Latin America as Romeo and Juliet. From the Caribbean and Brazil the guava and its paste ran through the whole of the Hispanic and Lusophone tropics, and onward to the diasporas of Miami and beyond; across the Indian Ocean it reached Egypt, where its thick nectar became a national drink, and South Africa, where it was bottled, jellied, and baked into puddings. From a perishable fruit of the American forest, the guava had become one of the most widely grown and eaten fruits of the entire tropical world.

India today grows more guava than any other country, and there the fruit is an everyday pleasure: the firm, crisp, under-ripe amrud sold from carts and sliced to order with a sprinkle of salt, black pepper, and chaat masala, and the Goan guava cheese perad cut into ruby squares. Across Latin America the guava is, above all, the paste: the goiabada of Brazil, eaten in slabs with Minas cheese as Romeu e Julieta; the pasta de guayaba of Cuba and the Caribbean, baked into the flaky pastelitos and set beside cheese; and the guava shells in syrup, casquitos, of the Cuban table. The Mexican kitchen drops fresh guava into the Christmas punch, ponche navideño, and blends it into agua fresca. In South-East Asia the green guava is the crisp, sour snack eaten with chilli-salt dips from Bangkok to Hanoi, and in the Philippines the ripe fruit is the souring heart of sinigang na bayabas, the sour soup. In Egypt the thick guava nectar, asir gawafa, is one of the most beloved of all juices, and in South Africa the fruit is canned, jellied, and baked into the rolled pudding guava roly-poly.

Beyond the kitchen the guava is prized as a nutritional powerhouse, its flesh carrying several times the vitamin C of an orange, and its leaves are brewed into a folk tea for the stomach across the tropics. The fruit's two relatives keep their own niches: the strawberry guava in Brazilian and Hawaiian preserves, and the feijoa as a cult fruit of New Zealand, made into chutney, crumble, and jam. Grown across every warm region of the earth, eaten fresh with salt, drunk as nectar, and set into the great fruit pastes of the Americas, the common guava is one of the most thoroughly globalised of all the fruits the New World gave the Old.