Scientific classification
Kingdom: Plantae
Division: Magnoliophyta
Class: Magnoliopsida
Order: Ericales
Family: Lecythidaceae
Genus: Bertholletia
Species: B. excelsa

Binomial name : Bertholletia excelsa

The Brazil nut is a South American tree “Bertholletia excelsa” in the family Lecythidaceae, and also the name of the tree's commercially harvested edible seeds.

The Brazil nut tree is the only species in the genus Bertholletia. It is native to the Brazil, eastern Bolivia, Guianas, Venezuela, eastern Colombia, and eastern Peru. It occurs as scattered trees in large forests on the banks of the Amazon, Rio Negro, and the Orinoco. The genus is named after the French chemist Claude Louis Berthollet.

Tree
It is a large tree, reaching 30–45 metres (100–150 ft) tall and 1–2 metres (3–6.5 ft) trunk diameter, among the largest of trees in the Amazon Rainforests.
It may live for 500 years or more, and according to some authorities often reaches an age of 1,000 years. The stem is straight and commonly unbranched for well over half the tree's height, with a large emergent crown of long branches above the surrounding canopy of other trees.
The bark is grayish and smooth. The leaves are dry-season deciduous, alternate, simple, entire or crenate, oblong, 20–35 centimetre long and 10–15 centimetres broad. The flowers are small, greenish-white, in panicles 5–10 centimetres long; each flower has a two-parted, deciduous calyx, six unequal cream-colored petals, and numerous stamens united into a broad, hood-shaped mass.

Brazil nuts almost exclusively produce fruit in virgin forests, as forests that are not virgin usually lack an orchid that is indirectly responsible for the pollination of the flowers.

The Brazil nut tree's yellow flowers can only be pollinated by an insect strong enough to lift the coiled hood on the flower and with tongues long enough to negotiate the complex coiled flower.
The orchids produce a scent that attracts small male long-tongued orchid bees (Euglossa spp), as the male bees need that scent to attract females. The large female long-tongued orchid bee pollinates the Brazil nut tree. Without the orchid, the bees do not mate, and therefore the lack of bees means the fruit does not get pollinated.

If both the orchids and the bees are present, the fruit takes 14 months to mature after pollination of the flowers. The fruit itself is a large capsule 10–15 centimetres diameter resembling a coconut endocarp in size and weighing up to 2 kilograms. It has a hard, woody shell 8–12 millimetres thick, and inside contains 8–24 triangular seeds 4–5 centimetres long (the "Brazil nuts") packed like the segments of an orange; it is not a true nut in the botanical sense.

The capsule contains a small hole at one end, which enables large rodents like the Agouti to gnaw it open.
They then eat some of the nuts inside while burying others for later use; some of these are able to germinate to produce new Brazil nut trees. Most of the seeds are "planted" by the Agoutis in shady places, and the young saplings may have to wait years, in a state of dormancy, for a tree to fall and sunlight to reach it. It is not until then that it starts growing again.
Capuchin monkeys have been reported to open Brazil nuts using a stone as an anvil

Nomenclature

Brazil nut seeds Despite their name, the most significant exporter of Brazil nuts is not Brazil but Bolivia, where they are called almendras. In Brazil these nuts are called castanhas-do-Pará (literally "chestnuts from Pará"), but Acreans call them castanhas-do-Acre instead. Indigenous names include juvia in the Orinoco area, and sapucaia in the rest of Brazil. And, though it has somewhat fallen into disuse since the latter part of the 20th century, a common slang term for the nuts in some regions of the United States was "nigger toes".

Cream nut is one of several historical names for the Brazil nut used in America.

Depiction of the Brazil nut in Scientific American Supplement, No. 598, June 18, 1887While classified by cooks as a nut, botanists consider Brazil nuts to be a seed and not a nut, since in nuts the shell splits in halves, with the meat separate from the shell

Nut production
Around 20,000 tonnes of Brazil nuts are harvested each year, of which Bolivia accounts for about 50%, Brazil 40% and Peru 10% (2000 estimates). In 1980, annual production was around 40,000 tons per year from Brazil alone, and in 1970 Brazil harvested a reported 104,487 tons of nuts.

Effects of harvesting
Brazil nuts for international trade come entirely from wild collection rather than from plantations. This has been advanced as a model for generating income from a tropical forest without destroying it. The nuts are gathered by migrant workers known as castanheiros.

Analysis of tree ages in areas that are harvested show that moderate and intense gathering takes so many seeds that not enough are left to replace older trees as they die. Sites with light gathering activities had many young trees, while sites with intense gathering practices had hardly any young trees.

Statistical tests were done to determine what environmental factors could be contributing to the lack of younger trees. The most consistent effect was found to be the level of gathering activity at a particular site. A computer model predicting the size of trees where people picked all the nuts matched the tree size data that was gathered from physical sites that had heavy harvesting

Uses
Foodstuff
Brazil nuts are 18% protein, 13% carbohydrates, and 69% fat. The fat breakdown is roughly 25% saturated, 41% monounsaturated, and 34% polyunsaturated. They are somewhat earthy in flavor. The saturated fat content of Brazil nuts is among the highest of all nuts, surpassing even macadamia nuts. Because of the resulting rich taste, Brazil nuts can often substitute for macadamia nuts or even coconuts in recipes.

Nutritionally, Brazil nuts are rich in selenium, although the amount of selenium varies greatly.
They are also a good source of magnesium and thiamine. Some research has suggested that selenium intake is correlated with a reduced risk of prostate cancer.This has led some commentators to recommend the consumption of Brazil nuts as a protective measure.. Subsequent studies about the effects of selenium on prostate cancer are inconclusive.

Other uses
As well its food use, Brazil nut oil is also used as a lubricant in clocks, for making artists' paints, and in the cosmetics industry.

The timber from Brazil nut trees is of excellent quality, but logging the trees is prohibited by law in all three producing countries (Brazil, Bolivia and Peru). Illegal extraction of timber and land clearances present a continuing threat.

The Brazil nut effect, where large items mixed with other smaller items (e.g. Brazil nuts mixed with peanuts) tend to rise to the top, is named after the species' large nuts.

The third quality
involves the pieces; the ones that that have been broken during the process. The broken nut is cut for its best conservation, best homogenization of size and presentation. Regularly are produced the following types:Type "Broken E" size: 1/3 to 2/3 of the seed
Type "Broken 5" size: less than 1/3 of the seed