Amazon walnuts (Bertholletia excelsa), also known as Brazil nuts, are the fruit of an tree species native to the highest elevations of the Amazon jungle. They are mainly found in Peru, Bolivia and Brazil. The wood of walnut trees from Brazil (not to be confused with wood from Brazil) is of excellent quality and has a variety of uses, from floors to heavy buildings. Both rural and Brazilian Bolivians rely on collecting and selling nuts from Brazil as their primary source of income.
The family of Brazil nuts, Lecythidaceae, belongs to the order Ericales, as do other well-known plants such as blueberries, blueberries, sapote, gutapercha, tea, phlox and persimmons. Brazil's walnut trees (Bertholletia excelsa) are the only species in the monotypic genus Bertholletia, named after the French chemist Claude Louis Berthollet. The fruit itself is a large capsule 10 to 15 cm (4 to 6 inches) in diameter, similar in size to a coconut endocarp and weighing up to 2 kg (4 pounds 7 oz). If you take them from the bag of shelled blended nuts mentioned above, you won't be able to spread them.
Because of this, although attempts have been made to plant trees in Brazil, natural cultivation has proven to be more reliable. The Brazil nut is a large tree, which reaches 50 m (160 ft) in height and has a trunk of 1 to 2 m (3 ft 3 in to 6 ft 7 in) in diameter, making it one of the largest trees in the Amazon rainforest. Walnut wood from Brazil is prized for its quality in carpentry, flooring and heavy construction. The fruit and its nut shell, which contains the edible Brazil nut, are relatively large and can weigh up to 2 kg (4 lb 7 oz) in total weight.
In North America, as early as 1896, walnuts from Brazil were sometimes referred to by the slang term “fingers in black”, a vulgarity that gradually ceased to be used as racial insult became socially unacceptable. Nuts usually contain radium, a radioactive element, and one kilogram of nuts has an activity between 40 and 260 becquereles (1 and 7 nanocuries). At a reference amount of 100 grams (3.5 oz), Brazil nuts provide 659 calories and are a rich source (20% or more of the daily value, DV) of dietary fiber (30% DV), thiamine (54% DV), vitamin E (38% DV), magnesium (106% DV), phosphorus (104% DV), manganese (57% DV) and zinc (43% DV). Brazil nut (Bertholletia excelsa) is a South American tree from the Lecythidaceae family, and is also the name of the tree's edible seeds harvested commercially.
However, despite their popularity, many of us are clueless about the fact that almost all of Brazil's nuts come from rainforests and are harvested by hand by harvesters who live in the woods. As Manuel Guariguata, CIFOR's principal scientist on ecology and management of tropical forests, told me from his office in Peru, “Brazil's walnut is the only internationally traded nut that comes from nature, making it very unique.”.