Nature-Singapore: 2. Killer fig trees

on 23rd February 2023

Weeping Fig (Ficus benjamina), Peradeniya Botanic Gardens, Sri Lanka.

Of the many fig species found in Singapore, three are common stranglers that cause problems to our wayside trees.  These are the Weeping Fig (Ficus benjamina) (above), the Bodhi Tree (F. religiosa) (below) and the Banyan Tree (F. benghalensis) (below).

Bodhi Tree (Ficus religiosa), Shwedagon Paya, Yangon, Myanmar.

Banyan Tree (F. benghalensis), Ala Moana Regional Park, Honolulu

The Bodhi Tree (F. religiosa) is sacred to Buddhists as Lord Buddha found enlightenment sitting under the shade of this tree.  This tree is also sacred to Hindus and Jains. The Banyan Tree (F. benghalensis) is revered by Hindus, as Lord Krishna rests on the leaves of the tree.

Strangling fig growing on a Rain Tree (Samanea saman) with a prominent root anchoring in the ground, 2006.

Birds deposit the seeds of these strangling figs onto the branches with their droppings. When a seed germinates, it grows a pair of seed leaves and a slender root. This root grows downwards and once it touches the ground it will take in nutrients and water from the soil to nourish the seedling. The seedling grows in size and the root thickens. At the same time the seedling will give out branches and more roots.

Strangling fig on Sindora sp., Bukit Timah Campus, 1982.

As more roots grow and anchor in the ground, they thicken and fuse together, finally forming a thick layer around the host trunk. In due course the host tree will be strangle to death as its trunk will not be able to increase in girth.

A tree with trunk nearly covered by roots of a Ficus sp., Phuket 1988

Cross-section of a tree trunk showing the host trunk surrounded by the strangling roots of the fig specimen (Old Botany Department Museum).

Our practice has been to remove strangling figs whenever found growing on our wayside trees and rightly so. In cases where the tree had been “semi strangled” as the tree along Stevens Road (below), the practice was to chop down the tree, as in this case. But was there a necessity to chop down the tree? After all, the strangled tree was attractive, at least to me. And it did not mean that once the fig killed the host tree, the spot alone the road would be treeless. A fig will always takes it place.

Tree with stem covered with criss-cross strangling roots along Stevens Road, 1981.

Now how many of us are familiar with fig trees? Those who are unfamiliar, may be familiar with their figs. After all, there is an edible fig (F. carica) available fresh or dried. If still not familiar, how about fig leaves. The Christian Bible mentions that Adam and Eve used fig leaves to cover their nakedness in the Garden of Eden.

Dried figs from the supermarket.

The pollination of figs makes an interesting story. The fig is actually a compound structure. Break into the fig and you will find numerous tiny flowers. Female fig wasps, the pollinating agent, will force their way into the fig through the small opening at the top covered with interlocking bracts. Once inside, the female wasps, already covered with pollen from an earlier visit, will pollinate the female flowers. During this short period, the blind and wingless male wasps, will emerge from the gall flowers and seek out the female to inseminate them. The male wasps then die. These inseminated female wasps will find their way out of the ripening fig. The male flowers, mostly found around the opening of the fig, transfer their pollen onto the departing wasps. These female wasps will then seek out figs in the same or other trees to lay their eggs in the gall flowers. While doing so they transfer the pollen they are carrying onto the female flowers. The female wasps then die inside the fig. So, when you eat a fig, will you be eating the fig wasps?

Longi-section of F. auriculate fig showing numerous flowers. The entry into the fig is on the left, the stalk is on the right.

Wee Yeow Chin

Singapore

23rd February 2023

If you like this post please tap on the Like button at the left bottom of page. Any views and opinions expressed in this article are solely those of the authors/contributors, and are not endorsed by the Lee Kong Chian Natural History Museum (LKCNHM, NUS) or its affiliated institutions. Readers are encouraged to use their discretion before making any decisions or judgements based on the information presented.

YC Wee

Dr Wee played a significant role as a green advocate in Singapore through his extensive involvement in various organizations and committees: as Secretary and Chairman for the Malayan Nature Society (Singapore Branch), and with the Nature Society (Singapore) as founding President (1978-1995). He has also served in the Nature Reserve Board (1987-1989), Nature Reserves Committee (1990-1996), National Council on the Environment/Singapore Environment Council (1992-1996), Work-Group on Nature Conservation (1992) and Inter-Varsity Council on the Environment (1995-1997). He is Patron of the Singapore Gardening Society and was appointed Honorary Museum Associate of the Lee Kong Chian Natural History Museum (LKCNHM) in 2012. In 2005, Dr Wee started the Bird Ecology Study Group. With more than 6,000 entries, the website has become a valuable resource consulted by students, birdwatchers and researchers locally and internationally. The views and opinions expressed in this article are his own, and do not represent those of LKCNHM, the National University of Singapore or its affiliated institutions.

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