Syzygium cumini, jambul, jambolan, jamblang, or jamun, is an evergreen tropical tree in the flowering plant family Myrtaceae. Syzygium cumini is native to Bangladesh, India, Nepal, Pakistan, Sri Lanka, the Philippines, and Indonesia. The name of the fruit is sometimes mistranslated as blackberry, which is a different fruit in an unrelated family.
The tree was introduced to Florida, USA in 1911 by the USDA, and is also now commonly grown in Suriname and Trinidad and Tobago. In Brazil, where it was introduced from India during Portuguese colonization, it has dispersed spontaneously in the wild in some places, as its fruits are eagerly sought by various native birds such as thrushes, tanagers and the Great Kiskadee. This species is considered an invasive in Hawaii, USA. It is also illegal to grow, plant or transplant in Sanibel, Florida.
Syzygium cumini is also known as jambul/jambhul/jambu/jambula/jamboola, Java plum, jamun, jaam/kalojaam, jamblang, jambolan, black plum, Damson plum, Duhat plum, Jambolan plum or Portuguese plum. Malabar plum may also refer to other species of Syzygium. This fruit is called Jamun in [Konkani], Hindi, Urdu and Punjabi, Neredu Pandu in Telugu, Naaval Pazham in Tamil, Naaval Pazham in Malayalam, Nerale Hannu in Kannada, Kalojam or Jam in Bengali, Jamukoli in Oriya and Jambu in Gujarat. In the Philippines, common names include duhat in the Tagalog-speaking regions, lomboy in the Cebuano-speaking areas, lumboy in Northern Luzon and inobog in Maguindanao. It is called Dhanbu in Maldives and Dhuwet/Juwet in Javanese. Among its names in Portuguese are jamelão, jambo, jambolão, jalão, joão-bolão, manjelão, azeitona-preta, baga-de-freira, brinco-de-viúva and guapê, always with lower case, the early four derived from the Konkani name jambulan. They are called rotra in the Malagasy language (Madagascar). It is called reyang dut in Malay especially in the northern part of Malay Peninsula.
A slow growing species, it can reach heights of up to 30 m and can live more than 100 years. Its dense foliage provides shade and is grown just for its ornamental value. At the base of the tree, the bark is rough and dark grey, becoming lighter grey and smoother higher up. The wood is water resistant. Because of this it is used in railway sleepers and to install motors in wells. It is sometimes used to make cheap furniture and village dwellings though it is relatively hard to work on.
The leaves which are an aroma similar to turpentine, are pinkish when young, changing to a leathery, glossy dark green with a yellow midrib as they mature. The leaves are used as food for livestock, as they have good nutritional value.
Syzygium cumini trees start flowering from March to April. The flowers of are fragrant and small, about 5 mm in diameter. The fruits develop by May or June and resemble large berries. The fruit is oblong, ovoid, starts green and turns pink to shining crimson black as it matures. A variant of the tree produces white coloured fruit. The fruit has a combination of sweet, mildly sour and astringent flavour and tends to colour the tongue purple.
The pulp of the fruit, extracts from the bark and seeds is of great benefit when it comes to lowering of blood glucose level. Taking dried extract of the seeds orally, greatly reduces the blood sugar and glucosuria. 
Syzygium cumini has been spread overseas from India by Indian emigrants and at present is common in former tropical British colonies.
Nutrients and phytochemicals
Nutritional information for S. cumini leaves and fruit are detailed here.
Cultural and religious significance
According to Hindu tradition, Rama subsisted on the fruit in the forest for 14 years during his exile from Ayodhya. Because of this, many Hindus regard S. cumini as a 'fruit of the gods,' especially in Gujarat, India, where it is known locally as jamboon.
In Maharashtra, S. cumini (locally known as jāmbhūḷ Marathi :जांभूळ) leaves are used in marriage pandal decorations. There is famous Marathi song "Jambhul pikalya zada khali...". The seeds are used in tisanes for diabetes
This tree is called Neredu(నేరేడు) in Telugu. Besides the fruits, wood from Neredu tree is used in Andhra Pradesh to make bullock cart wheels and other agricultural equipment. Culturally, beautiful eyes are compared to this fruit. In the great epic of India Mahabharatha Sri Krishnas'[Lord Vishnu] body color is compared to this fruit as well.
There is a very famous legend that is associated with Auvaiyar (also Auvayar) (Tamil: ஔவையார்), a prominent female poets/ethicist/political activist of Sangam period (Tamil literature), and Naval Pazham(Jambu) in Tamil Nadu. Auvaiyar, believing to have achieved everything that is to be achieved, said to have been pondering over her retirement from Tamil literary work while resting under Naval Pazham tree. But she was met with and was wittily jousted by a disguised Lord Murugan (regarded as one of the guardian deities of Tamil language), who later revealed himself and made her realize that there is still a lot more to be done and learnt. Following this awakening, Auvaiyar is believed to have undertaken a fresh set of literary works, targeted at children.
In Kannada the tree is called Nerale mara and its fruit are kempu Nerale Hannu Nerale hannu is widely used by diabetes patients as it was thought to cure the same. The bears like this fruit. This tree is found everywhere in rural areas of Karnataka.