The mangosteen tree is slow-growing, attains 20 to 82 ft
(6-25 m) in height, has dark-brown or nearly black, flaking bark. Its short-stalked leaves are elliptic, leathery and thick, dark-green, slightly glossy above and yellowish-green and dull beneath.  The flowers are 1 1/2 to 2 in (4-5 cm) wide and fleshy and may be male or hermaphrodite on the same tree. The rind (pericarp) of the edible fruit is deep reddish purple when ripe. The fragrant flesh is sweet and creamy, citrusy with a touch of peach flavor.  It is closely related to other edible tropical fruits such as button mangosteen and lemon drop mangosteen.

Cutting through the shell, one finds edible flesh, botanically defined as an aril, shaped like a peeled tangerine but bright white, about 3-5 cm in diameter, nested in a deep red outer pod. Depending on the fruit size and ripeness, there might be seeds in the aril segments. The seeds, however, are not palatable unless roasted. The number of aril pods is directly related to the number of petals on the bottom of the pericarp. On average, a mangosteen has 5 aril segments (round up figure). The plant does not start producing fruit until around 15 years old, which is somewhat an impediment to cultivation. 

The outer shell of the fruit, pericarp (rind), is firm (softens during riping), typically 4-6 cm in diameter, and contains astringent phytochemicals which discourage infestation by insects, fungi, plant viruses and bacteria. The same phytochemicals are pigments giving the exocarp its characteristic purple color, including phenolics acids, also called phenols. These pigments have antioxidant properties which afford the fruit further protection from ultraviolet radiation and free radicals generated during photosynthesis. Isolation of exocarp pigments has permitted their identity to be revealed as xanthones, mainly garcinol and mangostin [1], which, as phenolics, make the exocarp highly astringent and inedible.