Elephant apple
Dillenia indica is an evergreen forest tree, up to fifteen metres tall, whose native range extends from the Himalayas through the Indian subcontinents into Sri Lanka, and then east into southeast Asia and the Malay Archipelago. Large, stiff, prominently corrugated leaves, together with fragrant flowers, up to twenty centimetres wide, and fist-sized green-red fruits, have made this tree a popular ornamental throughout the tropics and subtropics for shade and novelty.
Each flower has thick, green, scoop-like sepals surrounding large, white petals. Inside these is a ball of numerous stamens around an ovary crowned with many, pale, flattened stigmas. Pollination, which is apparently by large bees, leads to the development of the fruit. However, the fleshy part of the fruit is produced not from the ovary but from the sepals which become fleshy as the fruit develops. The elephant apple produces small seeds, which are probably naturally dispersed by large mammals (especially elephants) eating the fruit.
In Dillenia indica’s native range, humans have used the acidic sepals of the fruit, with their flavour of unripe apples, for millennia in raw and cooked dishes. The species’ potential medicinal value was mentioned in Hendrik van Rheede’s (1636-1691) Hortus Indicus Malabaricus (1678), an account of plants found along the west coast of India, where some of the earliest illustrations of Dillenia indica in western botanical literature are found.
An accident of history associates the elephant apple with Oxford University. The German botanist Johann Jacob Dillenius (1684-1747) became Sherardian Professor of Botany in 1734. Trained as a physician, Dillenius’ botanical reputation brought him to the attention of William Sherard (1659-1728), one of the most prominent botanists in the early eighteenth-century Europe. In 1721, Sherard persuaded Dillenius to move to England as his assistant – helping to organise Sherard’s substantial herbarium and to compile a list of names of the world’s known plants. Sherard insisted Dillenius was made the first Sherardian Professor. Dillenius cared little for pretension, pomposity and the trappings associated with his position. Instead, he went on to forge a reputation as one of the best botanists to have ever held the Sherardian professorship. In 1736, the young Swedish botanist Carolus Linnaeus journeyed to Oxford specifically to see Dillenius; the two men maintained an active friendship for the next eleven years. In 1737, Linnaeus memorialised Dillenius in the name Dillenia because, as Linnaeus stated, it has ‘the showiest flower and fruit, so Dillenius among botanists’.
Further reading
Druce GC and Vines SH 1907. The Dillenian Herbaria. An account of the Dillenian collections in the herbarium of the University of Oxford. Clarendon Press.
Hooker, WJ 1857. Dillenia speciosa. Showy dillenia. Curtis's Botanical Magazine t.5016.
Sekar N et al. 2016. How much Dillenia indica seed predation occurs from Asian elephant dung? Acta Oecologica 70: 53-59.
Stephen Harris