Hawaii's macadamia industry may trace back to a single Australian tree
In 2019, geneticists compared hundreds of wild Queensland macadamias with Hawaiian orchard trees and found that nearly all the Hawaiian crop descends from a small group near Gympie, perhaps one tree. That narrow ancestry leaves the world's most expensive nut vulnerable to disease, and its shell behaves rather like aluminium.
Macadamia is a genus of four evergreen tree species in the protea family, native to north-eastern New South Wales and parts of Queensland, where the nuts were an important bushfood for Aboriginal peoples. It is the only widely grown food plant native to Australia. Ferdinand von Mueller named the genus in 1857 after John Macadam, a Scottish-Australian chemist and politician. Only two species are grown for food; the other two produce nuts containing cyanide-forming compounds. Several species once lumped into the genus, some from Sulawesi and New Caledonia, were moved to other genera after genetic studies in 2008.
The nut is the hardest edible one to crack. Its woody shell needs roughly 2,000 newtons of force, is five times harder than a hazelnut's, and has mechanical properties similar to aluminium. Ordinary nutcrackers fail, so specialist tools press on the micropyle, the small white dot on the shell. Factories use rotating steel rollers, and in South Africa usable kernel averages only 27.6 percent of the weight.
The first commercial orchard was planted in the early 1880s at Rous Mill near Lismore, but Hawaii built the industry. William H. Purvis planted imported seeds at Kapulena in 1882, large-scale planting began in the 1920s, and for over a century Hawaii led the world. South Africa has held the top spot since the 2010s, harvesting 87,000 tonnes in 2024, and global production reached 344,000 tonnes in 2025. Trees take 7 to 10 years to crop commercially but may bear for more than a century; slow harvesting helps explain why macadamias were the priciest nut in the world as of 2019.
Raw kernels are about three-quarters fat, mostly monounsaturated, and supply 740 kilocalories per 100 grams. They are toxic to dogs, causing weakness and paralysis of the hind legs within 12 hours, for reasons nobody yet understands, and to cats as well.
Source: Macadamia
