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Brazil nut

life science Maturity 9-11 Next article →

The Brazil nut, known scientifically as *Bertholletia excelsa*, refers to both a massive South American tree and its edible seeds. This tree belongs to the family Lecythidaceae. It is one of the largest and longest-lived species in the Amazon rainforest. Because it grows so large, it is a vital part of the tropical ecosystem. The tree is also a major commercial product. Its seeds are harvested for food, while its high-quality wood is used for construction.

Brazil Nut - Project Gutenberg eBook 11662
Brazil Nut - Project Gutenberg eBook 11662

As a tree, *Bertholletia excelsa* is a true giant. It can live for 500 years or even reach 1,000 years of age. The trunk is straight and often lacks branches for more than half its height. Above the surrounding forest canopy, it develops a large, emergent crown of long branches. The bark is smooth and grayish. Its leaves are oblong and broad, falling during the dry season. This structure allows the tree to reach sunlight that other trees cannot access.

The reproduction of the Brazil nut tree is a complex biological process. It relies almost entirely on pollination by large-bodied bees. These bees belong to genera such as *Bombus*, *Centris*, *Epicharis*, *Eulaema*, and *Xylocopa*. Because these specific bees need pristine forests to survive, the trees mostly reproduce in undisturbed habitats. After pollination occurs, the fruit takes 14 months to mature. The fruit is a large, woody capsule that can weigh as much as a coconut.

Brazil nut DSC05477
Brazil nut DSC05477

Inside the hard capsule, the seeds are arranged in a very specific way. There are between eight and 24 wedge-shaped seeds packed inside. They are organized like the segments of an orange. These segments can be stacked in up to three whorls. The polar ends of the middle whorl nestle into the upper and lower whorls. To reach these seeds, nature provides a way in. The capsule has a small hole at one end. Large rodents called agoutis gnaw this hole to access the seeds.

Brazil nuts
Brazil nuts

Agoutis play a critical role in the life cycle of the tree. They eat some seeds and bury others in caches for later use. Some of these buried seeds eventually germinate into new saplings. These young trees often stay in a state of dormancy for years. They must wait for a larger tree to fall so sunlight can reach them. This relationship between the rodent and the tree helps maintain the forest. Interestingly, capuchin monkeys have also been observed using stones as anvils to crack the nuts open.

Brazil nut production is a major global industry centered in South America. In 2023, the world produced 75,910 tonnes of Brazil nuts in their shells. Brazil and Bolivia are the most important producers, accounting for 91% of the world total. Most of these nuts come from wild harvests rather than plantations. Migrant workers known as *castanheiros* or *castañeros* gather the nuts. This method is an economic model that allows people to earn money without destroying the forest. However, intense gathering can be a threat. If too many seeds are taken, there are not enough left to replace old trees.

From a nutritional standpoint, Brazil nuts are incredibly dense. They consist of 66% fats, 14% protein, and 12% carbohydrates. They are a significant source of magnesium, phosphorus, and zinc. Most notably, they are famous for their high selenium content. A single 28g serving contains about 544 micrograms of selenium. This is ten times the Daily Value of 55 micrograms. Because selenium is toxic in large amounts, experts suggest eating only a few nuts at a time to avoid selenosis.

Brazil nuts
Brazil nuts

Beyond food, the Brazil nut tree has many other uses. The wood is prized for carpentry, flooring, and heavy construction. The oil from the nuts is used as a lubricant for clocks. It is also used in making paints, soaps, and perfumes. The hard shells can be pulverized to create an abrasive for polishing metals and ceramics. Even the charcoal from the shells can be used to purify water. This makes the tree a highly versatile resource for both humans and the environment.

Castanha-copl6
Castanha-copl6
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Brazil nut DSC05477.JPG
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File:Castanha-copl6.JPG
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