Macadamia**_ is a genus of four species of trees indigenous to Australia and constituting part of the plant family Proteaceae. They are native to north eastern New South Wales and central and south eastern Queensland. The tree is commercially important for its fruit, the macadamia nut /ˌmækəˈdeɪmiə/ (or simply "macadamia"). Other names include Queensland nut, bush nut, maroochi nut, bauple nut, and Hawaii nut. In Australian Aboriginal languages, the fruit is known by names such as bauple, gyndl, jindilli, and boombera. Previously, more species with disjunct distributions were named as members of this genus Macadamia. Genetics and morphological studies more recently published in 2008 show they have separated from the genus Macadamia, correlating less closely than thought from earlier morphological studies. The species previously named in the Macadamia genus may still be referred to overall by the descriptive, non-scientific name of macadamia; their disjunct distributions and current scientific names are:
- New Caledonia endemic genus Virotia in 1975 having only the type species, then by 2008 all six endemic species
- North eastern Queensland, Australian endemic genus and species Catalepidia heyana in 1995
- North eastern Queensland and Cape York Peninsula, Australia, three endemic species of Lasjia in 2008; in Australia still informally described as northern macadamias
- Sulawesi (Indonesia) two endemic species of Lasjia in 2008, based on the 1952 name M. hildebrandii and the 1995 name M. erecta
Macadamia is an evergreen genus 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, 6–30 cm (2–10 in) long and 3–13 cm (1–5 in) broad, with an entire or spiny-serrated margin. The flowers are produced in a long, slender, simple raceme 5–30 cm (2–10 in) long, the individual flowers 10–15 mm (0.4–0.6 in) long, white to pink or purple, with four tepals. The fruit is a very hard, woody, globose follicle with a pointed apex, containing one or two seeds.
The German-Australian botanist Ferdinand von Mueller gave the genus the name Macadamia in 1857 in honour of the Scottish-Australian chemist, medical teacher, and politician John Macadam.