Argan oil is an oil produced from the kernels of the endemic argan tree, that is valued for its nutritive, cosmetic and numerous medicinal properties. The tree, a relict species from the Tertiary age, is extremely well adapted to drought and other environmentally difficult conditions of southwestern Morocco. The species Argania once covered North Africa and is now endangered and under protection of UNESCO. The Argan tree grows wild in semi-desert soil, its deep root system helping to protect against soil erosion and the northern advance of the Sahara. This biosphere reserve, the Arganeraie Biosphere Reserve, covers a vast intramontane plain of more than 2,560,000 hectares, bordered by the High Atlas and Anti-Atlas Mountains and open to the Atlantic in the west. Argan oil remains one of the rarest oils in the world due the small and very specific growing area. Argan trees were first reported by the explorer Leo Africanus in 1510. An early specimen was taken to Amsterdam where it was cultivated by Lady Beaufort at Badminton c1711.