Macadamia is agenus of fourspecies of trees in theflowering plant familyProteaceae.[1][2] They are indigenous to Australia—specifically, northeasternNew South Wales and central and southeasternQueensland. Two species of thegenus are commercially important for their fruit, themacadamia nut/ˌmækəˈdeɪmiə/ (or simplymacadamia). Global production in 2025 was 344,000 tonnes (379,000 short tons).[3] Other names includeQueensland nut,bush nut,maroochi nut orbauple nut.[4] It was an important source ofbushfood for theAboriginal peoples.
Fresh macadamia nut with husk orpericarp cut in halfStages of aMacadamia integrifolia nut: unripe, ripe, husk peeled, deshelledRoasted macadamia nuts with sawn nutshell, one cracked open
The nut was first commercially produced on a wide scale inHawaii, where Australian seeds were introduced in the 1880s, and which for more than a century was the world's largest producer.[5][6] South Africa has been the world's largest producer of the macadamia since the 2010s.
The macadamia is the only widely grown food plant that is native to Australia.[7]
Macadamia is a genus ofevergreen trees that grows 2–12 m (7–40 ft) tall.
The leaves are arranged inwhorls of three to six,lanceolate toobovate orelliptic inshape, 60–300 mm (2+1⁄2–12 in) long and30–130 mm (1+1⁄8–5+1⁄8 in) broad, with an entire or spiny-serrated margin. The flowers are produced in a long, slender, and simpleraceme 50–300 mm (2–12 in) long, the individual flowers10–15 mm (3⁄8–9⁄16 in) long, white to pink or purple, with fourtepals. The fruit is a hard, woody, globosefollicle with a pointed apex containing one or twoseeds. The nutshell ("coat") is particularly tough and requires around 2000N to crack. The shell material is five times harder thanhazelnut shells and has mechanical properties similar toaluminum. It has aVickers hardness of 35.[8][9]
extreme south east Queensland and northern New South Wales
Nuts fromM. jansenii andM. ternifolia containcyanogenic glycosides.[10][11] The other two species are cultivated for the commercial production of macadamia nuts for human consumption.
Previously, more species withdisjunct distributions were named as members of this genusMacadamia.[2] Genetics andmorphological studies published in 2008 show they have separated from the genusMacadamia, correlating less closely than thought from earlier morphological studies.[2] The species previously named in the genusMacadamia may still be referred to overall by the descriptive, non-scientific name of macadamia.
Formerly included in the genus
LasjiaP.H.Weston &A.R.Mast, formerlyMacadamia until 2008
Lasjia erecta(J.A.McDonald & R.Ismail) P.H.Weston & A.R.Mast; synonym, base name:Macadamia erectaJ.A.McDonald & R.Ismail A treeendemic to the island ofSulawesi, Indonesia. First described by science in 1995.[12]
The macadamia tree is usually propagated bygrafting. 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. Macadamias prefer fertile, well-drained soils, a rainfall of 1,000–2,000 mm (40–80 in), and temperatures not falling below 10 °C (50 °F) (although once established, they can withstand light frosts), with an optimum temperature of 25 °C (80 °F). The roots are shallow, and trees can be blown down in storms; like mostProteaceae, they are also susceptible toPhytophthora root disease. As of 2019, the macadamia nut is the most expensive nut in the world, which is attributed to the slow harvesting process.[16]
AMacadamia integrifolia /M. tetraphylla hybrid commercial variety is widely planted in Australia and New Zealand; Dr. J. H. Beaumont discovered it. It is high in oil but is not sweet. New leaves are reddish, and flowers are bright pink, borne on long racemes. It is one of the quickest varieties to come into bearing once planted in the garden, usually carrying a useful crop by the fourth year and improving from then on. It crops prodigiously when well pollinated. The impressive, grape-like clusters are sometimes so heavy they break the branchlets to which they are attached. Commercial orchards have reached 18 kg (40 lb) per tree by eight years old. On the downside, the macadamias do not drop from the tree when ripe, and the leaves are a bit prickly when one reaches into the tree's interior during harvest. Its shell is easier to open than that of most commercial varieties.
A pureM. tetraphylla variety from Australia, this strain is cultivated for its productive crop yield, flavour, and suitability for pollinating 'Beaumont.'
A South AfricanM. integrifolia /M. tetraphylla hybrid cultivar, it has a sweet seed, which means it must be cooked carefully so that the sugars do not caramelise. The sweet seed is usually not fully processed, as it generally does not taste as good, but many people enjoy eating it uncooked. It has an open micropyle (hole in the shell), which may let in fungal spores. The crack-out percentage (ratio of nut meat to the whole nut by weight) is high. Ten-year-old trees average 22 kg (50 lb) per tree. It is a popular variety because of its pollination of 'Beaumont,' and the yields are almost comparable.
AM. integrifolia /M. tetraphylla hybrid, this is a rather spreading tree. On the plus side, it is high-yielding commercially; 17 kg (37 lb) from a 9-year-old tree has been recorded, and the nuts drop to the ground. However, they are thick-shelled, with not much flavour.
In 2024,South Africa was the leading producer of macadamia nuts, with 87,000 tonnes,[17] up from 77,000 tonnes in 2023[18] and 54,000 tonnes out of global production of 211,000 tonnes in 2018.[19] Macadamia is commercially produced in many countries of Southeast Asia, South America, Australia, and North America havingMediterranean,temperate ortropical climates.[19]
The first commercial orchard of macadamia trees was planted in the early 1880s by Rous Mill, 12 km (7.5 mi) southeast ofLismore, New South Wales, consisting ofM. tetraphylla.[20] Besides the development of a small boutique industry in Australia during the late 19th and early 20th centuries, macadamia was extensively planted as a commercial crop inHawaii from the 1920s onward. Macadamia seeds were first imported into Hawaii in 1882 byWilliam H. Purvis, who planted seeds that year atKapulena.[21] The Hawaiian-produced macadamia established the well-known seed internationally, and in 2017, Hawaii produced over 22,000 tonnes.[22]
In 2019, researchers collected samples from hundreds of trees inQueensland and compared their genetic profiles to samples from Hawaiian orchards. They determined that essentially all the Hawaiian trees must have descended from a small population of Australian trees fromGympie, possibly just a single tree.[23] This lack of genetic diversity in the commercial crop puts it at risk of succumbing to pathogens (as has happened in the past tobanana cultivars). Growers may seek to diversify the cultivated population by hybridizing with wild specimens.
Screw-type macadamia nut cracker on a plate of unshelled macadamias
Macadamias are the world's hardest edible nut to crack.[24] Since ordinarynutcrackers apply insufficient force,[25] various types of specialist macadamia nut crackers are available, many of which apply force to themicropyle, visible as a white dot, to fracture the shell.[24]
For commercial scale deshelling, rotating steel rollers are used.[25] In South Africa, the average crack-out rate, meaning the ratio of usable nut to discarded shell, is 27.6% nut to 72.4% waste.[25]
Macadamia allergy is a type offood allergy to macadamia nuts which is relatively rare, affecting less than 5% of people withtree nut allergy in the United States.[26] Macadamia allergy can cause mild to severe allergic reactions, such asoral allergy syndrome,urticaria,angioedema, vomiting, abdominal pain,asthma, andanaphylaxis.[27] Macadamia allergy can also cross-react with other tree nuts or foods that have similar allergenic proteins, such ascoconut,walnut,hazelnut, andcashew.[28] The diagnosis and management of macadamia allergy involves avoiding macadamia nuts and their derivatives, reading food labels carefully, carrying anepinephrine auto-injector in case of severe reactions, and consulting a doctor for further testing and advice.
Macadamias aretoxic to dogs.Ingestion may result in macadamia toxicity marked byweakness and hind limb paralysis with the inability to stand, occurring within 12 hours of ingestion.[29] It is not known what makes macadamia nuts toxic in dogs.[30] Depending on the quantity ingested and the size of the dog, symptoms may also include muscle tremors, joint pain, and severe abdominal pain. In high doses of toxin, opiate medication may be required for symptom relief until the toxic effects diminish, with full recovery usually within 24 to 48 hours.[29]
Macadamias are also toxic to cats, causing tremors, paralysis, joint stiffness, and high fever.[31]
The trees are also grown asornamental plants in subtropical regions for their glossy foliage and attractive flowers. The flowers produce a well-regarded honey. The wood is used decoratively for small items.[35]Macadamia species are used as food plants by thelarvae of someLepidoptera species, includingBatrachedra arenosella.[citation needed]
Macadamia seeds are often fed tohyacinth macaws in captivity. These largeparrots are among the few animals, other than humans, capable of cracking the shell and removing the seed.[36]
Allan Cunningham was the first European to encounter the macadamia plant in Australia.[37]
1857–1858
German-Australian botanistFerdinand von Mueller gave the genus the scientific nameMacadamia. He named it after his friendJohn Macadam, a noted scientist and secretary of the Philosophical Institute of Australia.[38]
1858
'Bauple nuts' were discovered inBauple, Queensland; they are now known as macadamia nuts.
Walter Hill, superintendent of theBrisbane Botanic Gardens (Australia), observed a boy eating the kernel without ill effect, becoming the first nonindigenous person recorded to eat macadamia nuts.[39]
1860s
King Jacky, an aboriginal elder of the Logan River clan, south of Brisbane, Queensland, was the first known macadamia entrepreneur in his tribe and he regularly collected and traded the macadamias with settlers.[40]
1866
Tom Petrie planted macadamias at Yebri Creek (near Petrie) from nuts obtained from Aboriginals atBuderim.[41]
The first commercial orchard of macadamias was planted at Rous Mill, 12 km fromLismore, New South Wales, by Charles Staff.[43]
1889
Joseph Maiden, an Australian botanist, wrote, "It is well worth extensive cultivation, for the nuts are always eagerly bought."[44]
1910
The Hawaiian Agricultural Experiment Station encouraged the planting of macadamias on Hawaii'sKona District as a crop to supplement coffee production in the region.[45]
Ernest van Tassel formed the Hawaiian Macadamia Nut Co. in Hawaii.[47]
1925
Tassel leased 75 acres (30 ha) on Round Top in Honolulu and began Nutridge, Hawaii's first macadamia seed farm.[48]
1931
Tassel established a macadamia-processing factory on Puhukaina Street inKakaako, Hawaii, selling the nuts as Van's Macadamia Nuts.
1937
Winston Jones and J. H. Beaumont of theUniversity of Hawaii's Agricultural Experiment Station reported the first successful grafting of macadamias, paving the way for mass production.[49]
1946
A large plantation was established in Hawaii.[50][51]
1953
Castle & Cooke added a new brand of macadamia nuts called "Royal Hawaiian," which was credited with popularizing the nuts in the U.S.
1991
A fourth macadamia species,Macadamia jansenii, wasdescribed, being first brought to the attention of plant scientists in 1983 by Ray Jansen, a sugarcane farmer and amateur botanist fromSouth Kolan in CentralQueensland.[52]
1997
Australia surpassed the United States as the major producer of macadamias.[45]
2012–2015
South Africa surpassed Australia as the largest producer of macadamias.[53][54]
^abcMast, Austin R.; Willis, Crystal L.; Jones, Eric H.; Downs, Katherine M.; Weston, Peter H. (July 2008). "A smallerMacadamia from a more vagile tribe: inference of phylogenetic relationships, divergence times, and diaspore evolution inMacadamia and relatives (tribe Macadamieae; Proteaceae)".American Journal of Botany.95 (#7):843–870.Bibcode:2008AmJB...95..843M.doi:10.3732/ajb.0700006.ISSN1537-2197.PMID21632410.
^"Macadamias Global Statistical Review".INC International Nuts and Dried Fruit. International Nut and Dried Fruits Council. 13 March 2025. Retrieved23 November 2025.{{cite web}}: CS1 maint: url-status (link)
^J. Andrew McDonald and Ismail, R. (September 1995). "Macadamia erecta (Proteaceae), a New Species from Sulawesi".Harvard Papers in Botany.1 (#7). Harvard University Herbaria:7–10.JSTOR41761991.
^The proceedings of Philosophical Institute of Victoria, now theRoyal Society of Victoria Rev: Mueller F (1857) Account of some new Australian plants.Transactions of the Philosophical Institute of Victoria 2: 62–77; Burke & Wills: The Scientific Legacy of the Victorian Exploring Expedition by E B Joyce & D A McCann,Royal Society of Victoria 2011
^McKinnon, Ross. "Hill, Walter (1819–1904)".Australian Dictionary of Biography. Canberra: National Centre of Biography, Australian National University.Archived from the original on 13 February 2018. Retrieved12 February 2018.
^McConachie, Ian (1980)."The Macadamia Story"(PDF).California Macadamia Society Yearbook.26:41–47.Archived(PDF) from the original on 11 January 2014. Retrieved11 January 2014.
^"Nut Growing Experiments",The Queenslander, 8 October 1931, p. 13
^Hamilton, Richard; Ito, Philip; Chia, C.L.Macadamia: Hawaii's Dessert Nut(PDF). University of Hawaii. p. 3.Archived(PDF) from the original on 24 December 2016. Retrieved10 July 2017.
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