Ficus (PROSEA Timbers)

Plant Resources of South-East Asia Introduction

List of species

Ficus L.

Protologue: Sp. pl. 2: 1059 (1753); Gen. pl., ed. 5: 482 (1754).

Family: Moraceae

Chromosome number: x= 13; 2n= 26 for the vast majority of species, 2n= 52 for few species

Vernacular names

• Ficus, fig (En)
• Figuier (Fr)
• Indonesia: ara, bunut, karet
• Malaysia: ara, ara kelumpong (stem figs), ara tanah (geocarpic figs), nunok (strangling figs, Dusun, Sarawak), giwit (geocarpic figs, Dusun, Sarawak)
• Papua New Guinea: Papua New Guinea fig (trade name)
• Philippines: balete (Filipino). Burma (Myanmar): nyaung
• Thailand: sai
• Vietnam: chi da, dề, sung.

Origin and geographic distribution

Ficus comprises about 1000 species and occurs in tropical and subtropical regions, about half of them in Malesia. Few species are found in warm temperate areas.

Uses

Few Ficus species become large enough to be useful for timber. The wood of these is used for temporary construction, mouldings, interior work, cladding, drawers, concrete formwork, dugouts, laundry tubs, small domestic articles, fruit crates, floats and firewood. The wood of some species is suitable for the production of matches and matchboxes. A low grade plywood can be manufactured from the wood. It may become valuable for the production of fibreboard.

The fruits of some species are edible but are generally not sought after or prized. Some species have poisonous fruits. The latex has been used medicinally, mainly to cover and cure wounds, and as a wax in dyeing batik cloth; that of F. elastica Roxb. ex Hornem. is the source of India rubber and was once cultivated before para rubber ( Hevea brasiliensis (Willd. ex A.L. Juss.) Müll. Arg.) was introduced to the region. The latex is also used as birdlime and in Papua New Guinea for sealing leaks in canoes, whereas that of some species is highly toxic and applied as dart poison. The tough and fibrous bark of a few species is a well-known raw material for rough cordage and matting and used to be used for clothing; it is still used for bow strings. Young leaves of several species are eaten raw in salads or cooked with meat wrapped in them, the latter dish is considered a delicacy in the highlands of New Guinea. They have also been used as fodder, and leaves of other species are applied as sandpaper or to scour cooking pots. Several species are planted as wayside trees. One of these is F. benjamina which is often regarded as a sacred tree and is a popular pot plant in temperate regions. F. benghalensis is sacred to Hindus and Buddhists. F. racemosa and F. nota (Blanco) Merr. are used for slope, gully and river bank stabilization as they produce a deep and wide-spreading root system. As natural regeneration of F. variegata is easy, it has been proposed as green manure and cover crop.

Production and international trade

Small amounts of Ficus timber are traded, most often in mixed consignments of lightweight hardwood. In 1987 Japan imported 442 logs from Papua New Guinea comprising 0.7% of the total of imports from that country. In the same year, Japan imported very small amounts of ficus from the Solomon Islands. In Papua New Guinea ficus timber is ranked in MEP (Minimum Export Price) group 5 and fetched a minimum export price of US$ 40/m³for logs in 1992. In 1996 Papua New Guinea exported a volume of about 12 000 m³of ficus logs at an average free-on-board (FOB) price of US$ 100/m³.

Properties

Ficus yields a lightweight to medium-weight hardwood with a density of 190-740 kg/m³at 15% moisture content. Heartwood pale yellow-brown or various shades from yellow to pink-grey, not clearly differentiated from the sapwood; grain straight, interlocked to deeply interlocked; texture moderately coarse to coarse and uneven due to abundant parenchyma; darker-coloured streaks produced by parenchyma giving rise to watered-silk figure on tangential surfaces and palisade effect on radial surfaces. Growth rings indistinct, when present marked by marginal parenchyma; vessels medium-sized to very large, solitary and in radial multiples of 2-3(-6), occasionally filled with gum-like deposits and tyloses; parenchyma abundant, in wide apotracheal bands, conspicuous, and paratracheal vasicentric; rays medium-sized to moderately broad; with a tendency to ripple marks in some species and observed in F. benjamina , but usually absent.

Shrinkage of the wood upon air drying is low to medium. The wood seasons well, but is susceptible to sap-stain and slight degrade in the form of twisting, cupping and bowing. The sawn timber should be treated immediately with anti-stain chemicals. It takes about 2.5 months to air dry boards 13 mm thick, and about 3 months for boards 38 mm thick, which is fairly rapid. The wood is soft and not strong. It is very easy to work, and although a little woolly; a fairly smooth finish can be obtained. The wood is non-durable and not resistant to termite and fungal attack. The sapwood is susceptible to Lyctus . It is extremely easy to treat with preservatives.

The sapwood of F. benghalensis has a gross energy value of 18 565 kJ/kg.

See also the tables on microscopic wood anatomy and wood properties.

Botany

Evergreen or sometimes deciduous, woody, epiphytic climbers or stranglers, creepers, shrubs or small to large, trees up to 40(-50) m tall, or banyans, i.e. trees whose branches send down aerial roots that thicken ("pillar-roots") which function as props; bole fairly straight in tree-like species, sometimes fluted, up to 100(-190) cm in diameter, sometimes heavily buttressed; bark surface smooth, often pale grey, sometimes whitish or brown, sometimes lenticellate, inner bark yellowish, exuding white or yellow latex. Leaves arranged spirally, alternate or opposite, simple or palmately lobed, symmetrical to asymmetrical, dentate to entire, often with glands below in the axil of the lateral or basal veins or abaxial at the apex of the petiole; stipules free or connate. Inflorescence axillary or rami- to cauliflorous, sometimes subterranean, solitary or clustered, monoecious or gynodioecious, with the flowers set inside an urn-shaped receptacle (syconium; a fig). Flowers unisexual; tepals 2-8, free or joined; stamens 1-7; ovary unilocular with a single ovule, style single. Infructescence a more or less fleshy fig; individual fruit a drupelet. Seedling with epigeal germination; cotyledons emergent; hypocotyl elongated; all leaves arranged spirally.

The strangling figs start as epiphytic plants and send down aerial roots that eventually form a false trunk composed of a trellis-work of interlacing and anastomosing roots. Many species have more than one kind of leaf (heterophylly).

The symbiotic relation of figs with specialized wasps is well-known. Figs can only be pollinated by female agaonid wasps ( Hymenoptera , Chalcidoidea , Agaonidae ). The wasp species are highly species-specific. Fig species are divided into 2 groups: monoecious species and gynodioecious ones. In the first the wasps arrive when only female flowers are receptive. They enter the fig via the osteole, a bract-covered apical pore. Once inside they pollinate the female flowers and deposit their eggs in the ovaries. As style length varies greatly within these figs and because the wasp can only reach the ovary of short-styled flowers, only some of the flowers obtain an egg, while in others the seed develops. Male and female wasps emerge after a few weeks, and mate takes place within the fig. The females then emerge from the fig and, in so doing pick up pollen from the newly mature anthers. Figs on a single tree mature at the same time, while different trees of the same species flower out of synchrony, thus inducing cross-pollination. The gynodioecious fig species carry either hermaphrodite figs or figs with female flowers only. In hermaphrodite ones the styles are uniformly short. Wasps can oviposit every female flower and such trees rear the pollinators' offspring and function as pollen donors. Figs with female flowers have long-styled flowers only. The wasps can only deposit pollen and such figs produce large amounts of seed.

An individual F. virens tree in Peninsular Malaysia flowered at intervals varying from 5 months to 3.5 years, whereas F. sumatrana Miq., a large strangler, flowered in a regular cycle of 4-5 months, apparently under endogenous control. During daytime the figs are eaten by birds (e.g. pigeons, hornbills, bulbuls, cassowaries), monkeys and squirrels. At night they are visited by bats and civet cats. Cauliflorous figs are eaten by deer and pigs. The latter also uproot the geocarpic figs. Even elephants, rhinoceros, tapir and wild cattle have been reported to feed on figs. As fig fruits are often available year-round, they constitute an extremely important forest food, a so-called keystone resource that sustains frugivorous animals at the famine period of the year when few species if any are fruiting.

F. obscura Blume forms cavities in parts of its twigs which open via slits and are inhabited by non-specific tree-dwelling ants. The plant produces a sugary secretion from extra-floral nectaries on the lower leaf surface.

In Asia and Australia the large genus Ficus has been subdivided into 4 subgenera and 14 sections and numerous smaller taxonomic groups.

Ecology

Ficus species are common and form an important element of lowland rain forest, both as canopy and understorey trees. Most species prefer perhumid forest, but several are found in areas with a monsoon climate and in teak forest, also in locations where the soil dries out. Ficus does not occur in mangrove vegetation but is often present in brackish swamps behind the mangrove. Ficus species are generally found below 1500 m altitude, some between 1500 and 2750 m or rarely up to 3200 m. Many species are epiphytic and/or strangling.

Silviculture Ficus can be propagated from seed and vegetatively. Per kg there are about 1.9-2.3 million dry seeds of F. racemosa and 2.1-2.5 million seeds of F. benghalensis . The drupelets are usually the unit of sowing. These cannot be stored without a serious decrease in viability. An 8% germination rate is achieved in 16-87 days in F. benjamina , in 8-40 days in F. grossularioides , in 18-34 days in F. microcarpa , in 11-12 days in F. sundaica and in 11-55 days in F. virens . In India pretreatment with hot water of 60C for 10 minutes was found to increase the germination of seed of F. benghalensis from 20% to 24% and of F. racemosa from 19% to 28% in 7-15 days. The tiny seedlings are pricked out twice, first in clumps and later individually. The young seedlings are sensitive to excess of water. Both large and small cuttings are used in vegetative propagation, but small cuttings are less successful. Except for F. racemosa and F. virens , most species are not resistant to fire. In the transition zone from mangrove to inland forest in Peninsular Malaysia, F. microcarpa makes up an important part of the trees over 5 cm in diameter, accounting for about 123 trees/ha (14% of the total) with a basal area of 2.4 m²/ha (12% of the total).

Genetic resources and breeding

There are no records of ex situ conservation of Ficus species, except for some, like F. benghalensis and F. benjamina , which are widely planted or cultivated. As most of the species are fairly common and widespread, the risk of genetic erosion seems comparatively low.

Prospects

It is unlikely that its importance as a timber tree will increase, because of the growth form of many Ficus species and the poor quality of the wood.

Literature

40, 70, 124, 146, 151, 163, 182, 206, 209, 260, 267, 300, 340, 348, 375, 387, 405, 406, 436, 464, 525, 543, 568, 678, 694, 740, 741, 760, 770, 780, 829, 831, 861, 889, 921, 933, 934, 955, 974, 1038, 1123, 1169, 1198, 1221, 1242.