Macadamia is a
genus of four
species of trees in the
flowering plant family
Proteaceae.[1][2] They are indigenous to Australia, native to northeastern
New South Wales and central and southeastern
Queensland specifically. Two species of the
genus are commercially important for their fruit, the macadamia nut/ˌmækəˈdeɪmiə/ (or simply macadamia). Global production in 2015 was 160,000 tonnes (180,000 short tons).[3] Other names include Queensland nut, bush nut, maroochi nut, bauple nut and, in the US, they are also known as Hawaii nut.[4] It was an important source of
bushfood for the
Aboriginal peoples.
The nut was first commercially produced on a wide scale in
Hawaii, where Australian seeds were introduced in the 1880s, and for some time, they were the world's largest producer.[5][6] South Africa has been the world's largest producer of the macadamia since the 2010s.
Macadamia is an
evergreengenus that grows 2–12 m (7–40 ft) tall.
The leaves are arranged in
whorls of three to six,
lanceolate to
obovate or
elliptic in
shape, 60–300 mm (2+1⁄2–12 in) long and 30–130 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 simple
raceme 50–300 mm (2–12 in) long, the individual flowers 10–15 mm (3⁄8–9⁄16 in) long, white to pink or purple, with four
tepals. The fruit is a hard, woody, globose
follicle with a pointed apex containing one or two
seeds. The nutshell ("coat") is particularly tough and requires around 2000
N to crack. The shell material is five times harder than
hazelnut shells and has mechanical properties similar to
aluminum. It has a
Vickers hardness of 35.[8][9]
Modern history
1828
Allan Cunningham was the first European to encounter the macadamia plant in Australia.[10]
1857 - 1858
German-Australian botanist
Ferdinand von Mueller gave the genus the scientific name Macadamia. He named it after his friend John Macadam, a noted scientist and secretary of the Philosophical Institute of Australia.[11]
1858
'Bauple nuts' were discovered in
Bauple, Queensland; they are now known as macadamia nuts.
Walter Hill, superintendent of the
Brisbane Botanic Gardens (Australia), observed a boy eating the kernel without ill effect, becoming the first nonindigenous person recorded to eat macadamia nuts.[12]
1860s
King Jacky, 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.[13]
1866
Tom Petrie planted macadamias at Yebri Creek (near Petrie) from nuts obtained from Aboriginals at Buderim.[14]
The first commercial orchard of macadamias was planted at Rous Mill, 12 km from
Lismore, New South Wales, by Charles Staff.[16]
1889
Joseph Maiden, an Australian botanist, wrote, "It is well worth extensive cultivation, for the nuts are always eagerly bought."[17]
1910
The Hawaiian Agricultural Experiment Station encouraged the planting of macadamias on Hawaii's
Kona District as a crop to supplement coffee production in the region.[18]
Ernest van Tassel formed the Hawaiian Macadamia Nut Co. in Hawaii.[20]
1925
Tassel leased 75 acres (30 ha) on Round Top in Honolulu and began Nutridge, Hawaii's first macadamia seed farm.[21]
1931
Tassel established a macadamia-processing factory on Puhukaina Street in
Kakaako, Hawaii, selling the nuts as Van's Macadamia Nuts.
1937
Winston Jones and J. H. Beaumont of the
University of Hawaii's Agricultural Experiment Station reported the first successful grafting of macadamias, paving the way for mass production.[22]
1946
A large plantation was established in Hawaii.[23][24]
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, was
described, being first brought to the attention of plant scientists in 1983 by Ray Jansen, a sugarcane farmer and amateur botanist from
South Kolan in Central
Queensland.[25]
1997
Australia surpassed the United States as the major producer of macadamias.[18]
2012–2015
South Africa surpassed Australia as the largest producer of macadamias.[26][3]
Nuts from M. jansenii and M. ternifolia contain
cyanogenic glycosides.[29][30] The other two species are cultivated for the commercial production of macadamia nuts for human consumption.
Previously, more species with
disjunct distributions were named as members of this genus Macadamia.[2] Genetics and
morphological studies published in 2008 show they have separated from the genus Macadamia, correlating less closely than thought from earlier morphological studies.[2] The species previously named in the genus Macadamia 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, formerly Macadamia 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 tree
endemic to the island of
Sulawesi, Indonesia. First described by science in 1995.[31]
The macadamia tree is usually propagated by
grafting and 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 most
Proteaceae, they are also susceptible to Phytophthora root disease. As of 2019, the macadamia nut is the most expensive nut in the world, which is attributed to the slow harvesting process.[34]
Cultivars
Beaumont
A Macadamia 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.
Maroochy
A pure M. tetraphylla variety from Australia, this strain is cultivated for its productive crop yield, flavour, and suitability for pollinating 'Beaumont.'
Nelmac II
A South African M. integrifolia / M. tetraphylla hybrid cultivar, it has a sweet seed, which means it has to 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.
Renown
A M. 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 2018,
South Africa was estimated as the leading producer of macadamia nuts, with 54,000 tonnes out of global production of 211,000 tonnes.[36] Macadamia is commercially produced in many countries of Southeast Asia, South America, Australia, and North America having
Mediterranean,
temperate or
tropical climates.[36]
History
The first commercial orchard of macadamia trees was planted in the early 1880s by Rous Mill, 12 km (7.5 mi) southeast of
Lismore, New South Wales, consisting of M. tetraphylla.[37] 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 in
Hawaii from the 1920s onward. Macadamia seeds were first imported into Hawaii in 1882 by
William H. Purvis, who planted seeds that year at
Kapulena.[38] The Hawaiian-produced macadamia established the well-known seed internationally, and in 2017, Hawaii produced over 22,000 tonnes.[39]
In 2019, researchers collected samples from hundreds of trees in
Queensland 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 from
Gympie, possibly just a single tree.[40] This lack of genetic diversity in the commercial crop puts it at risk of succumbing to pathogens (as has happened in the past to
banana cultivars). Growers may seek to diversify the cultivated population by hybridizing with wild specimens.
Macadamia allergy is a type of
food allergy to macadamia nuts which is relatively rare, affecting less than 5% of people with
tree nut allergy in the
United States.[42] Macadamia allergy can cause mild to severe allergic reactions, such as
oral allergy syndrome,
urticaria,
angioedema, vomiting, abdominal pain,
asthma, and
anaphylaxis.[43] Macadamia allergy can also cross-react with other tree nuts or foods that have similar allergenic proteins, such as
coconut,
walnut,
hazelnut, and
cashew.[44] The diagnosis and management of macadamia allergy involves avoiding macadamia nuts and their derivatives, reading food labels carefully, carrying an
epinephrine auto-injector in case of severe reactions, and consulting a doctor for further testing and advice.
Toxicity in dogs and cats
Macadamias are
toxic to dogs.
Ingestion may result in macadamia toxicity marked by
weakness and hind limb paralysis with the inability to stand, occurring within 12 hours of ingestion.[45] It is not known what makes macadamia nuts toxic, but its effects have only been reported in dogs.[46] 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.[45]
Macadamias are also toxic to cats, causing tremor, paralysis, stiffness in joints and high fever.[47]
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. The wood is used decoratively for small items.[48]Macadamia species are used as food plants by the
larvae of some
Lepidoptera species, including Batrachedra arenosella.[citation needed]
Macadamia seeds are often fed to
hyacinth macaws in captivity. These large
parrots are one of the few animals, aside from humans, capable of cracking the shell and removing the seed.[49]
^
abcMast, Austin R.; Willis, Crystal L.; Jones, Eric H.; Downs, Katherine M.; Weston, Peter H. (July 2008). "A smaller Macadamia from a more vagile tribe: inference of phylogenetic relationships, divergence times, and diaspore evolution in Macadamia and relatives (tribe Macadamieae; Proteaceae)". American Journal of Botany. 95 (#7): 843–870.
doi:
10.3732/ajb.0700006.
ISSN1537-2197.
PMID21632410.
^Shigeura, Gordon T.; Ooka, Hiroshi (April 1984).
Macadamia nuts in Hawaii: History and production(PDF). Research extension series. University of Hawaii. College of Tropical Agriculture and Human Resources.
ISSN0271-9916. Archived from
the original(PDF) on 22 September 2019. Retrieved 1 June 2020.
^The proceedings of Philosophical Institute of Victoria, now the
Royal 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. Retrieved 12 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. Retrieved 11 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. Retrieved 10 July 2017.
^"Macadamia nuts, raw, per 100 g". Conde Nast for the USDA National Nutrient Database, release SR 21. 2014. Archived from
the original on 14 January 2016. Retrieved 14 January 2016.