Jamun or naaval, is a member of one of the largest tree radiations in the world. It is a host plant for moths and butterflies, like the hungry Tussock moth caterpillar advancing towards its leaves in the image above.
The jamun tree belongs to Myrtaceae, a plant family that originated in Gondwana, a landmass combining South America, Africa, Arabia, Antarctica, Australia and the Indian subcontinent. The myrtle family is distributed across the world with many species producing aromatic oils (eucalyptus, clove) and fleshy fruit (guava, jamun). This family hosts Syzygium, the largest plant genus in the world, with over a thousand species distributed across tropical and subtropical Africa, India and Southeast Asia. (A genus is a higher hierarchical level in the biological classification of organisms and many species may be subsumed within it. For example, jamun – Syzygium cumini, and clove – Syzygium aromaticum, are two different species within the genus Syzygium.)
Syzygium originated in the Australia-New Guinea region around 50 million years ago and expanded in its geographic range through multiple dispersal events, many of them jumps between islands. Recent evidence shows that these stepwise dispersals isolated populations, which diverged from each other leading to speciation events. The rapidity of this process gave rise to a plethora of species over a short period of time, many of which are tricky to tell apart based only on their appearance. Syzygium flowers host many insects and its fruit attract birds, mammals and even reptiles.
Syzygium cumini is native to the Indian subcontinent and produces clusters of small white fragrant flowers in spring and early summer that are pollinated by bees and other insects. Its fruit go through shades of green, pink and purple as they ripen, where its mature delicious dark purple fruit are eaten by birds and small mammals. The tree has beautiful glossy dark green leaves worthy of poetry. One can explore when it flowers, fruits and sheds leaves across locations in India using citizen science data collected by SeasonWatch.
In his book 'Trees of Delhi', Pradip Krishen talks about two kinds of jamun. He says that botanists are unsure about the distinction, but jamun sellers in Delhi attest to their existence. Krishen refers to Syzygium cumini as 'jamun', which has smaller and more round fruit, and calls Syzygium nervosum 'rai jamun', which has larger and more elongated fruit.
One can see the naaval tree near the dish behind the IMSc main building (the terrace has a great view of its canopy) and by the road right outside the campus.
