Averrhoa carambola: Star fruit

Family: Oxalidaceae
Common name: Star fruit, Five-corner, Carambola

Star fruit tree is a small tropical tree that bears yellowish-green, star-shaped fruits almost through the year. They are very commonly found in India, favored for their unique sweet and sour taste.

The tree can grow to a height of 10-12 meters tall with a dense, spreading crown. The branches droop to the sides making the tree wider than its height. The leaves are alternate, dark green, glossy, and oval-shaped, and can grow up to 15-18 cm long.

The leaves are sensitive to light, folding up in the night or even when they are shaken vigorously. When in bloom, the tree looks very attractive with deep pink flowers growing thickly on the branches. The flowers are pinkish-white, bell-shaped, and fragrant blooming in thick clusters from late spring to early summer.

Star fruit tree flowers attract birds and bees to the garden, pollinating themselves and also other plants. The most distinctive feature of the tree is the thick, fleshy, light green fruits that are about 5-15 cm long and 3-6 cm in diameter.

When cut, the cross-section has a distinct star shape giving the tree its name. The fruit has five prominent ridges that run the length of the fruit, giving it its star-like shape. When ripe, the inside flesh is yellow and sweet. The fruits contain 10-12 small seeds that are thin and brown.

Fruits are eaten raw or used in salads, juices, pickles, or preserves. They are a rich source of Vitamin C, helping prevent infections and illnesses.

Parts of the star fruit tree have been used in the treatment of skin diseases, fever, high blood pressure, diabetes, and cough. The fruits are used in dyeing, and also as a stain remover. Softwood of the tree is used in making small implements and furniture.

They are closely related to the Averrhoa bilimbi or Bilimbi tree, the only two trees in the Averrhoa genus producing edible fruits.

Star fruit trees grow well in tropical countries with good rainfall. They can tolerate dry weather, water-logging, and winds. They make good garden trees due to year-round flowering and fruiting.

Propagation is through seeds and air layering.