Guava is a plant of the myrtle family scientifically known as Myrtaceae. It is represented by the genus Psidium with 100 species of tropical shrubs and small trees known. They are native to Mexico, Central America, and northern South America. They have now well established in the tropics and subtropics in Southeast Asia, Hawaii, the Caribbean, Florida and Africa. The most frequently encountered species of guava is the Apple guava variety.
Guavas are typical plants with tough and dark leaves. The leaves are arranged opposite on the stem and are elliptic, to ovate measuring 5-15 cm long. The flowers are white with five petals and numerous stamens. The genera Accara and Feijoa were formerly included in the genus Psidium. They are most frequently used as food plants by larvae of many lepidopteran insects. The bacterium Erwinia psidii causes rot diseases in Apple Guavas. The fruits are highly relished by humans, many mammals as well as by birds. The animals help in the dispersal of guava seeds to long distances along with their droppings. In some tropical regions including the Hawaii many varieties have become invasive species. Several species have also joined the category of rare species due to habitat destruction. One species particularly the Jamaican Guava has become completely extinct.
Guava wood is used for smoking meat in Hawaii. They are also used in the barbecue competitions in the United States. Cuba the leaves are also used in barbecues, providing a smoked flavor and scent to the meat. They are cultivated in many tropical and subtropical countries for their edible and highly nutritious fruits. Several species are cultivated for commercial purposes only. Apple Guava is available as a very popular variety on commercial basis all over the world. Mature trees of most species can tolerate colder temperatures up to 5°C but the young plants fail to survive. They are also grown as ornamental plants in the temperate regions. The guava fruit is about 4-12 cm long or round depending upon the species. The outer skin is usually hard with a bitter or sweet taste. When unripe the fruits are usually green but they become yellow, maroon or green when fully ripe. The fruits have a typical fragrance resembling like that of lemon rind but is less sharp. The pulp may be sweet or sour and white of pink in colour.
In Hawaii the fruit is eaten with soy sauce and vinegar. Sometimes a pinch of sugar and black pepper is also added along with soy sauce and vinegar to enhance the taste. In India and Pakistan the fruit is often eaten raw or along with salt or pepper. Fruit is often used to make fruit salads. In Asia guava pieces are often dipped in prune powder before eating. As the fruit contains high levels of pectin they are used in making candies, preserves, jellies, jams, marmalades. They are sometimes included in the category of superfruits as they are rich sources of dietary fiber, vitamins A and C, folic acid, and the dietary minerals, potassium, copper and manganese. They contain four times more vitamin C as that present in the oranges. They contain both Guavas contain both carotenoids and polyphenols. They are a part of folk medicine since ancient times. The extracts obtained from Apple Guava are used against cancer, bacterial infections, inflammation and pain. Essential oils obtained from guava also have some anticancer properties. Leaves are used to cure diarrhea. The bark is believed to possess antimicrobial properties and as an astringent.