Terminalia ferdinandiana, also called the gubinge, billygoat plum, Kakadu plum, green plum, salty plum, murunga or mador, is a flowering plant in the family Combretaceae, native to Australia, widespread throughout the tropical woodlands from northwestern Australia to eastern Arnhem Land. It has a high concentration of vitamin C in its fruit: recorded concentrations of 2300–3150 mg/100 g wet weight and occasionally as high as 5300 mg/100 g, compared with 50 mg/100 g for oranges, ranks among the highest known of any natural source.
Terminalia ferdinandiana is a slender, small to medium-sized tree growing up to 14 m (46 ft) in height, with creamy-grey, flaky bark and deciduous pale green leaves. The flowers are small, creamy-white, perfumed, and borne along spikes in the leaf axils towards the ends of the branches. Flowering is from September to December. (Southern hemisphere spring/summer.) The leaf blades are strongly discolorous with a broadly elliptic to broadly ovate, occasionally obovate shape and are 11 to 33 centimetres (4.3 to 13.0 in) in length with a width of 8.5 to 23 centimetres (3.3 to 9.1 in) and have a rounded apex. The inflorescences are 16 to 19 centimetres (6.3 to 7.5 in) long and are glabrous throughout.
The species epithet "ferdinandiana" was created by A.W. Exell in honor of the first European botanist to collect and describe Kakadu plum, Ferdinand Mueller, who had originally given the species the nomen illegitimum (illegitimate name), Terminalia edulis.
The tree is found along the coast in the Kimberley region of Western Australia as far west as Broome extending east into the Northern Territory. It grows in a variety of habitat including sandplains, floodplains, creek beds, ridges, among vine thickets and on the edges of areas of mangroves. It grows in sandy, peaty or clay soils around sandstone or ironstone. In the Northern Territory the tree is found mostly in the western portion of the top end from the Western Australian border to Arnhem Land but is found as far east as Limmen National Park. It is often found as part of Eucalypt communities.
The fruit known as Kakadu plum (or "billygoat" plum) is used as bush tucker or traditional medicine by Australian Aboriginal people. The roundish, light green fruits are usually eaten raw, although they can also be made into a jam. Kakadu plum contains a high oxalic acid content that may have toxicity when consumed. Kakadu plums taste "somewhat bland, but with a definite sour and astringent finish."
In Aboriginal languages
In Kundjeyhmi, the language of Kakadu National Park where the English name 'Kakadu Plum' originates, the fruit and tree are called anmarlak. In the closely related Kunwinjku language of West Arnhem Land, the word is manmorlak, or mandjiribidj in the Kuninjku dialect. In Yolŋu it is called ŋäṉ'ka-bakarra. The alternative English names of gubinge and murunga come from the Bardi language and eastern Arnhem languages respectively.
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