Antiaris (PROSEA)

Plant Resources of South-East Asia Introduction

List of species

Antiaris Lesch. (timber aspects)

Protologue: Ann. Mus. Natl. Hist. Nat. 16: 478 (1810).

Family: Moraceae

Chromosome number: x= unknown; A. toxicaria (several subspecies): 2n= 24, 28

• Antiaris (En, trade name), upas tree (En)
• Indonesia: upas (general), ancar (Javanese), tatai (Sumatra)
• Malaysia: terap (general), ipoh (Peninsular), tasem (Sarawak)
• Papua New Guinea: antiaris (En)
• Philippines: upas (Filipino)
• Burma (Myanmar): aseik
• Laos: 'nong²
• Thailand: yang nong (central, northern), yuan (peninsular)
• Vietnam: cây sui.

Antiaris is a monotypic genus. Its only species, A. toxicaria Lesch. (synonyms: A. africana Engl., A. macrophylla R. Br., A. welwitschii Engl.), is found throughout the Old World tropics, from West Africa to Madagascar, Sri Lanka, India, Indo-China, southern China, Thailand, throughout the Malesian region, the Pacific (east to Fiji and Tonga), and northern Australia.

The wood of A. toxicaria is used for light construction, interior finish, furniture, moulding, panelling, shuttering, strip flooring, pallets, fruit cases, crates, handles for non-striking tools, plywood, core veneers and when treated also for weatherboards and shingles. It is suitable for the production of blockboard.

The bark yields a latex which is one of the principal components of most dart and arrow poisons in South-East Asia. Seeds, leaves and bark are used as a febrifuge and the seeds also as an antidysenteric. The bark has also been used for dyeing and as a bark cloth to make rough clothing. The fruit is edible.

In general, the wood of A. toxicaria is used only locally or traded in mixed consignments of lightweight hardwood. Export from Papua New Guinea, however, is fair. In 1987 2.7% of all timber exported to Japan from Papua New Guinea was Antiaris, and in 1992 it ranked in MEP (Minimum Export Price) group 3, yielding a minimum export price for saw logs of US$ 50/m³. In 1996 Papua New Guinea exported about 6570 m³ of Antiaris logs at an average free-on-board (FOB) price of US$ 118/m³. In 1992 the export of "terap" (also including timber of Parartocarpus and the lightweight Artocarpus species) from Sabah amounted to almost 9000 m³, mainly as logs, with a total value of US$ 630 000.

A. toxicaria yields a lightweight hardwood with a density of (250-)390-540 kg/m³ at 15% moisture content. Heartwood almost white, pale yellow or pale yellow-brown, not clearly differentiated from the sapwood which is up to 8 cm wide; grain interlocked; texture moderately coarse to coarse and even; wood lustrous and with ribbon figure on quarter-sawn surface. Growth rings indistinct; vessels moderately large to very large, mostly solitary, some in radial multiples of 2-4(-more), rarely in clusters, often with dark-coloured extraneous deposits, tyloses sparse or absent; parenchyma moderately abundant, paratracheal vasicentric and aliform, occasionally confluent; rays medium-sized, not conspicuous on radial surface; ripple marks absent; wood with laticifers, sometimes appearing as brown dots on tangential faces.

Shrinkage upon seasoning is moderate and the wood dries rapidly with little degrade. The wood is soft and very weak. It is fairly easy to work with hand and machine tools, and is easy to saw, but sharp tools are required to prevent crumbling, particularly along the edges. Some tearing may occur in planing, but it produces a very lustrous surface. It nails, glues and polishes well and is easy to peel. The wood is non-durable, but both heartwood and sapwood are permeable to pressure treatment; a retention of 455 kg/m³ and 540 kg/m³ has been determined for heartwood and sapwood, respectively. Rapid conversion and the application of anti-stain chemicals upon felling and immediately after sawing are essential, as the wood is liable to sap-stain. The wood is susceptible to pinhole borers and dry-wood termites. The sapwood is susceptible to Lyctus. Sawdust may cause skin irritation and stomach pain.

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

• A sometimes deciduous, monoecious, small to large tree up to 45(-60) m tall; bole straight, branchless for up to 23 m, up to 180 cm in diameter, sometimes with steep buttresses up to 3 m high; bark surface smooth becoming slightly fissured, greyish-white, inner bark soft and fibrous, pale yellowish, exuding a creamy copious latex which soon darkens to dirty brown and becomes granular upon exposure; crown conical at first, dome-shaped at maturity. Twigs hairy.
• Leaves distichous, simple, entire to denticulate, rounded to slightly heart-shaped and slightly unequal at base; stipules free, caducous.
• Inflorescence on a short shoot, in leaf axils or below the leaves, subtended by involucral bracts, in groups of 2-4, the male ones below the female ones on the same twig. Male inflorescence a short-stalked discoid head with many flowers; each flower with 2-7 tepals and 2-4 stamens. Female inflorescence with 1-2 flowers, sessile or stalked; flower pear-shaped; perianth 4-lobed; ovary adnate to the perianth, 1-locular with a single ovule, styles 2.
• Fruit forming a drupaceous whole together with the enlarged, fleshy receptacle, ellipsoid to pear-shaped, velvety.
• Seedling with hypogeal germination; cotyledons not emergent; hypocotyl not elongated; epicotyl with a few scale leaves followed by spirally arranged, conduplicate, dentate leaves.

Trees develop according to Roux's architectural tree model, characterized by a continuously growing monopodial orthotropic trunk and plagiotropic branches. In a 27-year-old trial in Indonesia trees measured on average 17 m in height and 27 cm in diameter. In Java A. toxicaria flowers in June on the new shoots.

Formerly, A. toxicaria comprised several species, but is now regarded as a single, though variable species. It has been divided into 5 subspecies; subsp. toxicaria and subsp. macrophylla (R. Br.) C.C. Berg occur within the Malesian region, the first is found from Sri Lanka to Sulawesi, the second from the Philippines to Tonga. The size of the fruit increases from Africa to Polynesia.

Antiaris is found as a rare, scattered tree in primary forest up to 1500 m altitude. It is occasionally found in grassy savanna and on coastal plateaus. In Africa it occurs under semi-arid conditions.

A. toxicaria can be propagated by seed. About 70-90% of sown stones germinate in 18-89 days. Trees have a good self-pruning ability; they are not resistant to fire. In Ulu Kelantan, Peninsular Malaysia, a density of about 1 tree per 80 ha of natural forest has been observed, but elsewhere in Peninsular Malaysia it is probably even rarer.

Genetic erosion of A. toxicaria is difficult to assess: on the one hand, trees are not widely harvested throughout their natural area of distribution, on the other, they are rare in natural forest in Peninsular Malaysia.

Its good peeling properties make Antiaris acceptable for plywood production, but supply will surely limit an increase in use.

40, 70, 105, 125, 151, 162, 163, 205, 209, 227, 267, 300, 302, 304, 340, 348, 402, 436, 536, 740, 741, 758, 829, 831, 951, 974, 1038, 1087, 1218, 1221, 1242, 1248.

E. Boer & M.S.M. Sosef