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.
It should not be confused with Planchonia careya, with which it shares some common names.
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 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.
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