© Geoff Nichols
The swamp or hippo fig is the only indigenous fig species in the southern African region whose aerial roots develop into new stems like the banyan, Ficus benghalensis, of India. The rather romantic name of hippo fig originates from the coincidental co-occurrence of this tree and the hippopotamus in KwaZulu-Natal.
The swamp fig may grow as either a medium-sized tree or a shrub. The height is recorded as being between 12 and 25 m. It has a rounded, spreading crown and may spread further sideways (creating a grove) by sending down aerial roots which become new stems. The bark is mostly pale and smooth with some mottling. It becomes darker in older trees. A characteristic of all figs (and the family) is their milky sap.
The leaves are dark green, oval in shape and leathery in texture. The veins are conspicuous, yellowish white above and red below. The sheaths enfolding the apical buds and the leaf stalks are also red. As with all figs, the inflorescence is a syconium. The syconium is a unique feature of the fig: essentially it is a flowerhead that has closed in on itself to make a hollow sphere, lined by tiny flowers. The figs appear predominantly in spring, although they may be found all year round, and ripen to a brilliant red (first turning orange) in summer, a most attractive feature. The figs are slightly more flattened top and bottom than the common domestic fig, Ficus carica. The seeds are contained within the fig. It is quite similar in appearance to the giant-leaved fig, F. lutea, but the latter has yellow figs, the veins and leaf stalks are yellow and the apical bud has a silvery-coloured sheath.
Ficus trichopoda is a protected tree in South Africa and may not be disturbed or damaged in any way (including the harvesting of fruit).
Distribution and Habitat
As the name swamp fig suggests, the natural habitat is in swamps and swamp forests, not usually away from permanent water. It grows naturally from the northern coast of KwaZulu-Natal into Mozambique extending northwards. It is also found in northern Zambia where it extends northwards into Zaire and Tanzania. Although this tree has attractive features, it can become a bit untidy. It would suit the warmer parts of the country where there is little frost and where there is good water availability.
Derivation of name and historical aspects
The generic name Ficus is the classical Latin name for fig. The specific name trichopoda, translated from Latin, literally means hairy foot! This possibly refers to the hair-like appearance of the aerial roots as they develop into the 'feet' of the new stems. The tree has a name that, sadly, is no longer used: F. hippopotami. It was given by botanist Jacob Gerstner and refers to the hippopotamus. Possibly he, like the Zulu people, thought it significant that the occurrence of the animal and the tree was similar. The isiZulu name umvubu is actually the same for both the tree and the hippopotamus. The most likely reason for the discontinuance of the name is that it was found to be pre-dated by the current name. It is a taxonomic convention to use the earliest valid name.
There are about 750 species in the genus Ficus world-wide. Australasia has the greatest number of these, around 500. Approximately 110 are found in Africa with 48 in the southern portions. Within this range, the highest concentration of Ficus species lies in the more tropical climates. The economically important common fig, F. carica, has been cultivated since ancient times, the first recorded use being in Ancient Egypt. The familiar black and white mulberries (Morus nigra and M. alba respectively) are in the same family as the fig. They are significant in South Africa as the white mulberry is a declared invader and the black mulberry a proposed invader.
Duncan Butchart, a contributor to the book, Figs of southern and south-central Africa (Burrows & Burrows 2003), b elieves fig trees in general can be regarded as an ecosystem on their own and contribute immensely to the diversity of species where they grow. The pollination of figs is unique, complex and quite fascinating. It is performed by minute wasps (each fig species has a specific wasp pollinator) which enter the fig through a tiny hole called an ostiole. Figs which are ready for pollination release a specific chemical to attract pollinators. These are female wasps who battle their way into the fig and in the process lose their wings and most of their antennae! It is a one-way ticket as they do not leave the figs again. These receptive figs are in the female phase (female florets are receptive) and the wasp (who is carrying pollen from the fig where she was born) pollinates some of the florets and lays eggs in the ovules of others. The ostiole closes up after pollination and during this 'interfloral phase' the fig becomes ready for the 'male phase' and the wasp eggs complete their life cycle. When the male flowers produce pollen, the new generation of wasps emerge and mating takes place inside the figs. The wingless male wasps chew escape holes in the fig wall for the now mated females to leave. They are carrying pollen from the male flowers and set off to find a receptive fig and start the whole cycle again. When the male flowers have finished producing pollen, the fig ripens and becomes attractive to fruit-eating animals which disperse the seeds.
The figs themselves are an important food source for many animals including monkeys, bats, antelope and birds. Although the main fig crop is produced in summer, there are usually figs on the tree at any time of the year, which supply food when most other fruiting trees are bare. Fruit-eating birds which are attracted to figs include the African Green Pigeon, African Olive Pigeon, Bronze-naped Pigeon, turacos, hornbills, parrots, starlings and barbets. Butchart suggests that it is also possible that the fallen, floating, brilliantly coloured figs are attractive to waterfowl such as the African Pygmy Goose and also to fish species such as the Banded Tilapia and the Silver Catfish. Seed-eating birds such as doves, canaries and firefinches feed on any fallen, dried seeds beneath the tree as do some game birds such as guineafowl and francolin. Insect-eating birds and animals such as geckos feed on the wasps when they emerge from the figs. This emergence can happen en masse at times and will apparently even attract aerial feeders such as swallows and swifts who then roost nearby to take advantage of this boon.
The fig and wasp eaters themselves attract predators such as shrikes, raptors and snakes, making the swamp fig a centre of activity. Ficus trichopoda is host to Acrocerops ficina, one of the leaf-mining moth species (Family Gracillariidae).
The swamp fig is recorded as one of the first woody plants to colonize Papyrus swamp in Zambia. According to Burrows & Burrows (2003), in South Africa it may grow in association with, amongst others, the waterberry (Syzigium cordatum), the wild frangipani (Voacanga thouarsii), the quinine tree (Rauvolfia caffra), the raphia palm, (Raphia australis) and the wild cotton tree (Hibiscus tiliaceus), which are all swamp forest species. It can also be the dominant tree species in some areas.
Uses and cultural aspects
Ficus trichopoda has apparently been used successfully as a street tree along Riverside Drive in Durban, KwaZulu-Natal, where the crown has been kept pruned into shape.
Traditional uses include the use of the sap as birdlime and the making of twine and rope from the bark.
Growing Ficus trichopoda
Indigenous figs make wonderfully interesting and rewarding garden subjects, especially when one is planting to attract wildlife and preserve species diversity in the face of the sprawling urban environment. However, when one considers growing Ficus species in general, the first thing that comes to mind is the aggressive root system! This combined with the enormous size of some species means that their selection as garden specimens needs careful consideration. Although the swamp fig does not grow as huge as some fig species, it would better suit the larger garden (well away from pipes, walls, swimming pools and paving!) in the warmer parts of the country. It will apparently tolerate some mild frost. Keep well watered. F. trichopoda makes an attractive indoor container plant in a room with good light.
Geoff Nichols gives the following recommendations about cultivating Ficus species in his contribution to Figs of southern and south-central Africa : prepare a hole about 1 cubic metre. Replace one third by volume of the removed soil, with good compost and add to it one cup of super-phosphate fertilizer. Mix up well and put into the hole. Using the tree container as a measure, scoop out a hole the same size. Remove the container or bag and place the tree's root ball into the hole. Gently firm the soil around the stem. Ensure that its soil surface and that of the tree hole are the same. The root ball should certainly not be higher than the surrounding soil as it causes water to run away from where it's needed. Water the tree very well to eliminate any spaces that may have formed in the soil and to help the roots recover from any disturbance. This watering should continue on a weekly basis for at least the first season after planting.
The swamp fig may be propagated by seed, air layering and truncheons.
Harvest seed from figs which are soft to the touch-this indicates that they are ripe. Cut the figs open and allow the exposed seeds to dry in the shade for a day. Preferably sow seed in spring, therefore if ripe figs appear at the wrong time, store cleaned seed in the fridge until spring. Be aware that fresh seed will germinate more quickly (in about 10 days) than old seed. The drying fig can be crumbled gently in your fingers. The seed should ideally be separated from the pulp for sowing to help prevent fungal or bacterial problems. However, Geoff Nichols successfully germinates seedlings without doing this. He also recommends a seedling mix of equal quantities of sharp, clean river sand and vermiculite in large, flat, seed trays (30 x 20 x 7 cm). Cover the seed with a fine layer of the mix. The trays should be watered carefully with a fine mist to prevent the fine seed being washed away. Leave them in a well-ventilated area with good light. Do not allow them to dry out.
The seedlings may look weak until the first true leaves appear and then they will grow quickly. A very weak liquid fertilizer is recommended at this stage. Check for damping-off fungi (the tiny stem shrivels and the seedling collapses) and ensure that the ventilation is good. Some sunlight may help prevent fungal attack or use a fungicide drench registered for damping-off fungi, (active ingredient: captab). It also helps if the seedlings are not overcrowded in the seed tray. The seedlings can be pricked out and bagged in half-litre bags using a well-drained, sandy soil medium with plenty of humus added.
Air layering is done by selecting a suitable branch (bearing in mind this will be your new tree!) and wounding the bark almost all the way round-leave about 10% uncut. Apply rooting hormone, pack damp vermiculite and sand around the wound and cover with plastic, sealing at either end. It should take about six weeks for roots to appear. If roots are there, cut branch right off, plant in a bag and keep well watered until roots have established.
References and further reading
Cuttings and truncheons can be taken in early spring. Plant truncheon (about the thickness of your arm) with all leaves removed in the ground, one third below and two thirds above. Ficus trichopoda has also been successfully truncheoned by pegging the branches horizontally on the ground, with the dual function of erosion control and propagation.
- Burrows, J. & Burrows, S. 2003. Figs of southern and south-central Africa. Umdaus Press, Pretoria.
- Glen, H.F. 2004. SAPPI What's in a name? The meaning of the botanical names of trees. Jacana, Johannesburg.
- Henderson, L. 2001. Alien weeds and invasive plants. Agricultural Research Council, Pretoria.
- Kroon, D.M. 1999. Lepidoptera of southern Africa : host plants and other associations. D.M. Kroon & Lepidopterists' Society of Africa, Jukskei Park, South Africa.
- Leistner, O.A. (ed.). 2000. Seeds plants of southern Africa : families and genera. Strelitzia 10. National Botanical Institute, Pretoria.
- Nel, A., Krause, M. & Khelawanlall, N. 2003. A guide for the control of plant diseases. Department of Agriculture, Pretoria.
- Coates Palgrave, M. 2002. Keith Coates Palgrave Trees of southern Africa, edn 3. Struik, Cape Town.
- Pooley, E. 1993. The complete field guide to trees of Natal, Zululand and Transkei. Natal Flora Publications Trust, Durban.
- Scholtz, C.H. & Holm, E. 1985. Insects of southern Africa. Butterworths, Durban.
Walter Sisulu National Botanical Garden