Psidium is a large tropical American genus in the myrtle family. Psidium guajava is one of the best-known species in the genus. The precise origin of the guava is doubtful, as it has an ancient history of cultivation long predating the arrival of Europeans in the Americas. Guavas were amongst the first plants from the New World to be introduced into Europe, which also includes maize, chili pepper and tobacco.
The genus Psidium was described by the Swedish botanist Carl Linnaeus in his pioneering publication of the world’s plants in 1753. Linnaeus chose the name Psidium from the Greek psidias meaning pomegranate. This was a reasonable choice, since both guavas and pomegranates have largish, glossy yellow-green fruits that contain many small seeds. However, Linnaeus mistakenly cited its origin as Asian. Guavas had been introduced to Asia very early after European discovery of the Americas through the Acapulco-Manilla Spanish galleon route across the Pacific, which was possibly the cause of Linnaeus’ mistake; he was presumably informed that the species came from Asia.
Guavas are now widely cultivated and grow spontaneously throughout the tropical and subtropical regions of the world. Psidium guajava is an aggressive colonizer, as is its relative, the strawberry guava, Psidium cattleyanum. Both species have been so successful that they have become pests on some of the tropical islands where they were introduced by humans, for example Mauritius, the Philippines, the Galapagos islands and Hawaii. Populations have expanded to such great extents that they are occupying the habitats of native plants, which endangers their survival.
Guava trees have a smooth, glossy, copper-coloured bark, deep green leaves and fragrant white flowers that are pollinated by bees. The fruits are eaten by bats, monkeys and when they fall, ground-dwelling mammals. They are also pecked at by parrots when on the trees. The flesh inside the fruit is sweet, aromatic and refreshing, and can be either dark pink or creamy white. The many seeds they contain have exceptionally hard seed coats. In countries where guavas are commonly consumed, people sometimes break teeth when eating them, so their consumption is frowned upon by dentists. Despite this drawback, guavas are very healthy fruits, as they are exceptionally high in vitamin C and antioxidants. In South America, guava juice and ice-cream are very popular. Since the fruits are high in pectins, they can also be cooked and made into jams, preserves, biscuit fillings and tarts.
Clement, CR et al. 2010. Origin and domestication of native Amazonian crops. Diversity 2: 72-106.
Vaughan, J and Geissler, C 2009. The new Oxford book of food plants. Oxford University Press.
Urquía, D. et al. 2019. Psidium guajava in the Galapagos Islands: population genetics and history of an invasive species. PloS One 14: p.e0203737.