An African giant in Asia
On the island of Mannar, a peculiar tree is a curiosity. It is an African baobab (Adansonia digitata), a species native to the arid savannas of mainland Africa. The most famous of these trees, located in Pallimunai, is a behemoth with a circumference of 19.5 meters and a height of 7.5 meters. Its enormous, swollen trunk gives it a distinctive bottle-like shape, a feature that allows it to store vast quantities of water—up to 120,000 liters—to survive dry conditions.
This specific tree is the oldest and largest of its kind in Sri Lanka. A 2003 study estimated its age to be approximately 723 years, suggesting it began its life in the 14th century. There are about 40 baobabs in total recorded in Sri Lanka, with 34 of them found on Mannar Island. The presence of this small, isolated population of African trees thousands of kilometers from their native range is a botanical puzzle. Due to their rarity and age, these trees are now a protected species in Sri Lanka.
Competing origin theories
The most widely accepted theory for the baobab's presence in Sri Lanka involves Arab traders. Mannar was a historically significant port, and it is believed that traders brought the trees from Africa around the 15th century, or possibly as early as 700 AD. The leaves and fruit pulp were likely used as fodder for camels, which the traders also introduced to the island. The fruit, high in vitamin C, may have been consumed by the sailors as well. This human-assisted dispersal is common for the species, which has been introduced to many locations along ancient trade routes.
A more speculative hypothesis connects the trees to the supercontinent Gondwana. This theory posits that the Sri Lankan baobabs could be a relict population that has survived since the Indian subcontinent, Africa, and Madagascar drifted apart millions of years ago. Recent genomic studies, however, trace the origin of all baobab species to Madagascar about 21 million years ago. From Madagascar, two species undertook long-distance dispersal events, likely floating across the ocean, to reach mainland Africa and Australia. While this research complicates a simple Gondwanan story, it shows the genus can for long-distance travel. Definitive genetic analysis comparing the Sri Lankan population to African and Malagasy populations is still needed to resolve their precise origins.