Averrhoa carambola

star fruit


Averrhoa carambola

L. 1753

pronounced: av-er-OH-uh kah-ram-BOH-luh

(Oxalidaceae — the oxalis family)


common names: star fruit, carambola

Averrhoa is named for Averrhoes – Ibn Rushd (1149–1206?), an Arabian physician; carambola is the Latinized form of a native name for the fruit, probably that used in Malabar and adopted by the Portuguese. The tree probably originated in Sri Lanka and the Moluccas, but has been cultivated in southeast Asia and Malaysia for many centuries. It has been introduced to many other tropical countries, mainly as an ornamental.

This is a small, evergreen, multistemmed tree that usually grows 3 – 5 m in height, but can sometimes reach 10 m; a large specimen can attain a diameter of 15 cm near the base. The bark is light brown, smooth or finely fissured.

The alternate leaves are pinnate, 15 – 25 cm long,disposed more-or-less in a horizontal plane, shortly petiolate with 7 – 9 pendant leaflets. The leaves are sensitive to the touch like some of the mimosas.

The inflorescences are in panicles 2 – 5 cm long in the axils of old leaves; the flowers are pentamerous, with a calyx of 5 pink sepals surrounding the purple corolla; there are 5 fertile stamens and 5 staminodes, and also 5 slender united styles.

The fruit is a large indehiscent berry 5 – 8 cm long, its cross-section a 5-pointed star. It is yellowish green, becoming orange-yellow when ripe. Each cell of the fruit contains 5 seeds with arils.

Star fruits are refreshing when eaten fresh, or mixed with other fruits, or when processed into a drink. They are also stewed, pickled, or used for chutney and jam. There is a high oxalic acid content, which may be reduced by peeling off the wing edges before using. The fruit is very perishable, and needs to be used locally. There are two distinct classes of the fruit: the smaller, very sour type, richly flavoured, with more oxalic acid; and the larger, so-called ‘sweet’ type, mild-flavoured, rather bland, with less oxalic acid. There are some Brazilian cultivars that are very rich in vitamin C. The fruits naturally fall to the ground when fully ripe. For marketing and shipping they should be hand-picked while pale green with just a touch of yellow.
It is not too particular as to soil, and does well on sand, heavy clay or limestone, but will grow faster and bear more heavily in rich loam. It likes good drainage, and cannot stand flooding.

There is a Starfruit Flowermoth Diacrotricha fasciola that feeds on the buds and flowers of this plant.

The trees can be quite tricky to grow. They are widely grown from seed, though viability lasts only for a few days. The seedlings are very tender, and need good care. Air-layering (marcotting) is used in some areas, but root formation is slow, and results variable. Inarching is successful in India, and shield-budding in the Philippines. Trees can be top-worked by bark-grafting, a popular technique in Java.

The timber is generally available only in small dimensions. It is whitish, turning a light red, fairly soft, and close-grained. It is sometimes used for construction, and for making furniture and small implements.


Photographs taken in Picnic Bay, 2012, 2013
Page last updated 15th October 2018