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Magnificent Trees – Figs

Ficus benjamina Anzac Park

Judy with a huge, spreading Ficus benjamina
Anzac Park

Judy and I have met a lot of magnificent trees in our travels and it is difficult to choose a favourite group. I guess eucalypts are top of our list, but the one that takes the prize for a combination of tenacity and majesty are those species of the genus Ficus (figs) collectively known as the stranglers or banyans.

FIG FACTS

All members of the genus have a remarkable reproductive strategy involving the dependency on another life form, minute fig wasps.

There are up to 900 recognised species of Ficus, which occur across the tropics and subtropics. Species vary in size and form from rainforest giants of up to 50 metres to small trees and vines.

The larger fig species (stranglers or banyans) are most common in tropical and subtropical rainforests as tall emergent trees (standing out above the canopy). These substantial life forms have found their way into ornamental plantings in many cities and parks where they make outstanding, spreading specimens, for example the large Ficus benjamina in Anzac Park Brisbane (Post photo above and that is one tree).

The shorter species such as Sand Paper Figs are found in forests along water courses or rocky gullies. The vine forms are found growing on rocks in open forests and woodlands without any contact with the ground (lithophytes).

One species has been cultivated as a highly prized fruit tree and is widely grown in orchards and back yards. Sand Paper Figs are also edible and are being cultivated in gardens as bush tucker.

Figs (family Moraciae) have a milky, sticky sap and several species are cultivated for their latex-rich sap, which is used in the production of rubber. “V” shaped grooves are cut into the bark and the sap collected in containers. An individual tree is capable of filing a gallon bucket in six hours. Originally the species used was Ficus elastica (well named) from the subcontinent but Hevea braziliensisas (family Euphorbiaceae) from Brazil has displaced it in commercial plantings.

UNIQUE CHARACTERISTICS

The things that make figs remarkable include –

Their method of propagation. Strangler or banyan figs begin life as an epiphyte in the upper branches of trees or on rocks where their seed has been deposited in the droppings of birds etc – Epiphytes are plants growing on other plants but not deriving nutrition from the host plant, e.g. various ferns (such as Staghorns), orchids, mosses etc.

Their flowers are enclosed in a unique urn-shaped inflorescence (synconium sin-cone-ium). Some species are monoecious (synconia have both male and female flowers) and others are dioecious (trees are either male or female). The cultivated fig and Sand Paper Figs are dioecious.


The flowers are pollinated by small fig wasps (1-3mm long). There is a close relationship between figs and the wasps – fig wasps cannot reproduce outside of the fig fruit and figs cannot reproduce in the absence of the wasps indicating that this relationship has been a long one. With rare exceptions, each fig species has its own pollinator wasp species indicating their evolution is closely linked at the species level.

Some species bear their fruit on the larger branches and trunks (cormiflorous) and some species are deciduous.

Propagation

Fig fruits are eaten and dispersed by a number of birds (pigeons, fig parrots, Fig Birds) and mammals (possums and fruit bats). Their seeds are deposited in faeces on branches of trees (often high up), soil or rocks where they germinate. In the strangler figs, the seedling exists on the branches of trees as an epiphyte while extending its roots to the ground. This epiphyte stage is prolonged.

Once the roots reach the ground they thicken, proliferate and fuse until they surround the trunk of the host tree. In this stage the fig is no longer and epiphyte. The host tree eventually dies and is commonly believed to have been strangled, hence the common name Strangler Figs. However death is probably due to root competition at one end and light competition at the other.

Eventually the host trunk rots away leaving a hollow fig trunk formed of coalescing, fused roots. Strangler Figs have well developed plank buttresses which can extend as wave like expansions several metres from the base of the tree.

The three stages – going – going – gone!

My friend Tony Hiller (Mt Glorious Biological Centre) informs me that the inner angles of these buttress roots at the base of the trunk are a favourite nesting place for Noisy Pittas.

It is possible to observe all stages of this process when walking in subtropical and tropical rainforests. Remember to pause on the trail occasionally and look into the forest each side. The branches of figs act as great supports for epiphytes such as Staghorn and Elkhorn ferns, Orchids and Bird Nest Ferns, so look up as well.

Figs are a life force that cannot be denied. In urban situations this can be seen when they germinate in cracks in brick walls or rock faces. If they are allowed to grow in these situations the walls generally suffer damage from the relentlessly expanding roots. They are capable of growing on many substrates and we regularly find seedlings coming up amongst our potted plants.

Fig Wasps and Pollination

Figs are pollinated by tiny wasps in a process that has evolved into a complex symbiotic (mutually beneficial) and dependant relationship. Both figs and wasps have evolved remarkable modifications to assist this symbiosis.

Female fig flowers have developed into two forms. One is normal with a long pistil (pollen receptacle) and a gall flower with a short pistil. Female fig wasps place their eggs in the gall flowers where their larvae develop. The long pistil of the female flowers is too long for the wasps’ egg placer (ovipositor) to reach the ovum preventing egg placement. After pollination the ovum develops into a seed.


In dioecious figs (separate male and female plants) the male syncomium has both male flowers and female gall flowers – remarkable!

Female fig wasps have evolved special structures to gather pollen from male flowers. After fertilisation by wingless males the females with their pollen store burrow out and fly off to new synconia where they pollinate flowers in the new fruit as they move about ovipositing (laying eggs) in gall flowers.

Fig synconia support a number of other wasp species from different families. Some are parasites of fig wasps themselves and some are gall formers. In one species of Rhodesian fig a researcher reared 28 species of parasites and alternate gall formers as well as the fig wasps.

An Interesting Exercise

It is easy to rear these wasps yourself by collecting ripe figs from a tree and placing them in a glass jar with a very fine netting cover. I am always amazed by the number of wasps that emerge. Picking up fruit from the ground will not work as well because most of the wasps have already emerged and dispersed.

OUT AND ABOUT

Majestic Strangler Figs can be seen in any subtropical or tropical forest and in all stages of their life cycle.

Many Strangler Figs and larger non-strangler figs have been brought into cultivation as public plantings in parks where they exhibit an elegant, spreading growth form. Older botanic gardens and parks have mature examples of these magnificent trees

Some have been planted around the suburbs, but they are not trees for backyards. Their vigorous roots make short work of house foundations, paths and underground pipes. They make wonderful bonsai specimens and attractive potted plants. Careful management is required for potted specimens as they have aggressive roots that readily escape the pot even with a saucer under the pot – they climb out from the top. Again a life force not to be denied.

We encountered vine figs at Cania National Park just east of Monto in Queensland. They were growing on large boulders that have tumbled down the scree slopes.

The gallery below includes some of the Figs we have encountered on our travels – or Figs we have known and loved.

Below are a few locations of the many interesting historical Fig trees of Brisbane –

Brisbane Old Botanic Gardens

One species of banyan figs in India (Ficus benghalensis) sends down roots supporting its lateral branches which allow the lateral branches to extend further. One example in the Kolkata Botanic Gardens covers several acres. An excellent example of this species’ growth habit can be seen on the Old Botanic Gardens Brisbane (George Street). Enter the Gardens from George Street, turn right at the bottom of the steps and follow the path. You will recognise the tree when you see it overhanging the path and it has an information board with more interesting facts.

Fig Tree Reserve Brisbane

The three large fig trees on the triangular island at the junctions of Elizabeth, Creek and Eagle Streets in Brisbane include two deciduous Australian White Figs (Ficus virens) and an Indian evergreen Banyan (Ficus benghalensis). They were originally planted to give shade for workers beside the creek that ran from Roma Street through the city centre, along Creek Street emptying into the Brisbane River at Charlotte Street. A notice board provides historical details.

Mooney Memorial Fountain Brisbane

Another historical site occurs not far from here at the corner of Queen and Eagle Streets. An impressive 10 metre high sandstone memorial fountain was erected in the 1880’s. This ultimately became known as the Mooney Memorial fountain named after a fire fighter who lost his life fighting a Queen Street fire.

In 1930 a small-leaved species of fig (Ficus benjamina) was planted behind the fountain and now stands as a magnificent specimen shading the corner. The fountain was refurbished in 1988 and a plaque added in memory of Mooney and all fire fighters who have lost their lives in the line of duty.

Brisbane Parks

Parks around Brisbane include New Farm Park, Albert Park (overlooking Roma Street), Anzac Park (opposite the Toowong cemetery) and the A&M Lehman Memorial Park (in Vulture Street opposite the South Brisbane Town Hall). The most popular cultivated fig species is the small leaved Ficus benjamina and Anzac Park has an outstanding specimen.

Apart from these sites old fig trees can be encountered through many of the city’s older suburbs. Keep an eye out for them when you are out and about and look for them when walking in tropical and subtropical rainforests.

Further information on Brisbane city trees is available on a Brisbane City Council website. This site has a walking map with tree locations.

Acknowlegement –

The diagram of a sectioned fig fruit was taken from a scientific paper on Fig Wasps by J T Wiebes 1982. (Monographiae Biologicae: Ed J L Gressit: Dr W Junk Publishers, The Hague)

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