Nuts from M. jansenii and M. ternifolia contain cyanogenic glycosides. M. integrifolia and M. tetraphylla are the two species cultivated for the commercial production of macadamia nuts for human consumption.
Botany
Macadamia integrifolia is a small to medium-sized tree native to Australian rainforests. It is native to rainforests in southeast Queensland and extreme adjacent northern New South Wales, Australia. Macadamia tetraphylla is native to southern Queensland and northern New South Wales in Australia. Macadamia integrifolia trees grow to 15 metres (49 ft) in height, and M. tetraphylla grows up to 18 metres (59 ft).
M. tetraphylla usually has four leaves around each leaf node, whereas M. integrifolia has a variable leaf number but usually three. The shell of M. tetraphylla is often dimpled or rough, whereas that of M. integrifolia is smooth. The kernel is whitish and sweet and is eaten raw or roasted.
M. tetraphylla has a higher sugar content than M. integrifolia, which leads to burning when it is baked. Most commercial macadamias therefore come from M. integrifolia.
Cultivation and production
The macadamia tree is usually propagated by grafting. It does not begin to produce commercial quantities of seeds until it is 7-10 years old, but once established, it may continue bearing for over 100 years.
South Africa has been the world's largest producer of the macadamia since the 2010s. In 2024 it was the leading producer, with 87,000 tonnes. Macadamia is commercially produced in many countries of East Africa, Southeast Asia, South America, Australia, and North America having Mediterranean, temperate or tropical climates. Both species have not done well in the pure tropics, with no fully successful plantations less than 15 degrees from the equator.
The oil
Macadamia oil is liquid at room temperature. The oil content of the nut ranges from 65% to 75%. The oil contains approximately 60% oleic acid and 19% palmitoleic acid, with 1-3% linoleic acid and 1-2% α-linolenic acid. The abundance of palmitoleic acid is unusual in plant-based oils, and the oil is stable because of its low polyunsaturated fat content.
Macadamia oil is used in cooking as a frying or salad oil. It has a high smoke point and resistance to oxidative degradation, but it is primarily used in unheated forms, such as dressings and drizzles.
Other uses
The trees are also grown as ornamental plants in subtropical regions for their glossy foliage and attractive flowers. The flowers produce a well-regarded honey.
Species and conservation
Macadamia ternifolia is also called the Maroochy or Gympie nut, and its nuts are bitter and not edible. Older papers may therefore describe the commercial macadamia as ternifolia. M. integrifolia has a conservation status of Vulnerable and M. tetraphylla one of Endangered.
Macadamia fruits are woody and rounded, 2-3.5 cm in diameter. M. tetraphylla has dense foliage and toothed leaves 7 to 25 centimetres long, and its long pendant flowers range from white through creamy pink to purple. M. integrifolia can withstand temperatures as low as -4.4 °C. Macadamia has been introduced to Mexico, where it does well in the states of Michoacán and Jalisco.
Composition of the nut
The sugar content of the nut ranges from 6% to 8%, and together with the oil content it gives variable colors and texture when nuts are roasted under the same conditions. The oil consists mainly of unsaturated fatty acids and is similar in both species, although the ratio of unsaturated to saturated fatty acids appears slightly higher in M. integrifolia (6.2:1 compared with 4.8:1).
Production notes
Global production in 2025 was 344,000 tonnes. Major plantations in Costa Rica, at 10 degrees north, are said to produce much less than those in Hawaii at 19 to 22 degrees north, in one case 20% of the production, whereas plantations in Guatemala at 15 degrees north are successful. Many M. tetraphylla trees, or hybrids of M. tetraphylla and M. integrifolia, are grown in home orchards, and some people prefer the higher sugar of M. tetraphylla, especially for eating raw.
