Cacao tree

Theobroma cacao, also called the cacao tree and the cocoa tree, is a small (4–8 m (13–26 ft) tall) evergreen tree in the family Malvaceae, native to the deep tropical regions of the Americas. Its seeds, cocoa beans, are used to make chocolate liquor, cocoa solids, cocoa butter and chocolate. Leaves are alternate, entire, unlobed, 10–40 cm (3.9–15.7 in) long and 5–20 cm (2.0–7.9 in) broad. The flowers are produced in clusters directly on the trunk and older branches; this is known as cauliflory. The flowers are small, 1–2 cm (0.39–0.79 in) diameter, with pink calyx. The floral formula, used to represent the structure of a flower using numbers, is ✶ K5 C5 A(5°+5²) G(5). While many of the world's flowers are pollinated by bees (Hymenoptera) or butterflies/moths (Lepidoptera), cacao flowers are pollinated by tiny flies, Forcipomyia midges in the subfamily Forcipomyiinae. Using the natural pollinator Forcipomyia midges for Theobroma cacao was shown to have more fruit production than using artificial pollinators. The fruit, called a cacao pod, is ovoid, 15–30 cm (5.9–11.8 in) long and 8–10 cm (3.1–3.9 in) wide, ripening yellow to orange, and weighs about 500 g (1.1 lb) when ripe. The pod contains 20 to 60 seeds, usually called 'beans', embedded in a white pulp. The seeds are the main ingredient of chocolate, while the pulp is used in some countries to prepare refreshing juice, smoothies, jelly, and nata. Usually discarded until practices changed in the 21st century, the fermented pulp may be distilled into an alcoholic beverage. Each seed contains a significant amount of fat (40–50%) as cocoa butter. The fruit's active constituent is the stimulant theobromine, a compound similar to caffeine. Cacao (Theobroma cacao) belongs to the genus Theobroma classified under the subfamily Byttnerioideae of the mallow family Malvaceae. Cacao is one of 17 species of Theobroma. In 2008, researchers proposed a new classification based upon morphological, geographic, and genomic criteria: 10 groups have been named according to their geographic origin or the traditional cultivar name. These groups are: Amelonado, Criollo, Nacional, Contamana, Curaray, Cacao guiana, Iquitos, Marañon, Nanay, and Purús. The generic name is derived from the Greek for 'food of the gods'; from θεός (theos), meaning 'god', and βρῶμα (broma), meaning 'food'. The specific name cacao is the Hispanization of the name of the plant in indigenous Mesoamerican languages. The cacao was known as kakaw in Tzeltal, K'iche' and Classic Maya; kagaw in Sayula Popoluca; and cacahuatl in Nahuatl as 'bean of the cocoa-tree'. T. cacao is widely distributed from southeastern Mexico to the Amazon basin. There were originally two hypotheses about its domestication; one said that there were two foci for domestication, one in the Lacandon Jungle area of Mexico and another in lowland South America. More recent studies of patterns of DNA diversity, however, suggest that this is not the case. One study sampled 1241 trees and classified them into 10 distinct genetic clusters. This study also identified areas, for example around Iquitos in modern Peru and Ecuador, where representatives of several genetic clusters originated more than 5000 years ago, leading to development of the variety, Nacional cocoa bean. This result suggests that this is where T. cacao was originally domesticated, probably for the pulp that surrounds the beans, which is eaten as a snack and fermented into a mildly alcoholic beverage. Using the DNA sequences and comparing them with data derived from climate models and the known conditions suitable for cacao, one study refined the view of domestication, linking the area of greatest cacao genetic diversity to a bean-shaped area that encompasses Ecuador, the border between Brazil and Peru and the southern part of the Colombian-Brazilian border. Climate models indicate that at the peak of the last ice age 21,000 years ago, when habitat suitable for cacao was at its most reduced, this area was still suitable, and so provided a refugium for the species. Cacao trees grow well as understory plants in humid forest ecosystems. This is equally true of abandoned cultivated trees, making it difficult to distinguish truly wild trees from those whose parents may originally have been cultivated.