My spelling of “Brazil” is corrected constantly, so I should probably call these seed Brazil Nuts, but in South America (in both Spanish and Portuguese) the country is written as Brasil – so I prefer that spelling. I mean, don’t you get to decide how people spell your own name?
Along with Pecan, this is one of my favorite “nuts,” and I recall that as a child we’d be challenged to crack them open – a well-earned reward. I’m also the person who robs the nut mix of Brasil Nuts early in the party. Of course that is made easier by the “Brasil Nut Effect” – a physical outcome of their larger size, which means smaller nuts tend to settle to the bottom of the mix, stranding the larger Brasil Nuts atop the pile.
My sense is that Cooks regard these nuts as large objects found in a nut mix; you hardly see them sold or used otherwise.
Systematists are amused by this plant and its compatriots in the Lecythidaceae – the Monkey Pot family. Somewhere, on a branch of the great “tree of life” the Brasil Nut hangs out near Tea and Actinidia (Kiwi).
These large tropical trees produce amazingly sturdy and heavy fruit that open by forming a circular cap that falls off. Their seed, encased in a superhard testa (seed coat) are attached to the fruit by a fleshy and delicious stalk. Brasil Nut fruit are unusual in this group, in that the cap does not free itself from the fruit; animals have to carve into the thick wall to access seed trapped inside. But their larger cousins, called Monkey Pot trees, behave more normally – automatically opening. I envision monkeys pulling the seed from the “pot” (a fruit type called a Pyxidium), consuming the tasty seed stalk, and tossing the seemingly impenetrable seed to the ground.
Native to the lowland tropics of South America, Brasil Nut was only brought to attention of Europeans when scientifically described by Humboldt and Bonpland, as Bertholletia excelsa (a monotypic genus honoring the chemist Claude Louis Berthollet.) Much of the available harvest of these seed comes from trees growing naturally in tall forest.
(Search the WWW for: Seed coat anatomy and its relationship to seed dispersal in subfamily Lecythidoideae of the Lecythidaceae (The Brazil Nut Family), Chih-Hua Tsou and Scott A. Mori, 2002, Bot. Bull. Acad. Sin. 43:37-56). Also look in JSTOR for The Brazil Nut, by W. J. Y