Cerbera (PROSEA Timbers)

Plant Resources of South-East Asia Introduction

List of species

Cerbera L.

Protologue: Sp. pl. 1: 208 (1753); Gen. pl., ed 5: 98 (1754).

Family: Apocynaceae

Chromosome number: x= unknown;C. manghas: 2n= 40,C. odollam: 2n= 40

Vernacular names

• Grey milkwood (En, trade name)
• Indonesia: bintaro (Java)
• Malaysia: pongpong (Peninsular)
• Papua New Guinea: cerbera (general). Burma (Myanmar): kalwa
• Cambodia: krapur
• Thailand: teenpet (central)
• Vietnam: hải guả tủ, muróp sat, muróp xác.

Origin and geographic distribution

Cerbera comprises 7 species and is found from Madagascar and islands in the Indian Ocean to India, Burma (Myanmar), Indo-China, Taiwan and Thailand, throughout the Malesian region towards Melanesia and north-eastern Australia.

Uses

The wood of Cerbera is used for mouldings, interior trim, fruit cases, core veneer, match splints, shuttering, clogs, plain furniture and carving. The wood of C. manghas yields a good charcoal.

Several species are applied medicinally against aches and sores. C. manghas and C. odollam are well-known for their poisonous seeds, used amongst others to stupefy fish in the Philippines, and an excellent purgative can be prepared from their root and bark. The seeds contain an oil which has been used for making candles. The oil from the seeds of C. floribunda is rubbed on the skin to cure itch and colds. C. manghas is also planted as an ornamental.

Production and international trade

Small amounts of Cerbera logs are exported from Papua New Guinea and the Solomon Islands to Japan. In 1996 Papua New Guinea exported about 1000 m³of Cerbera logs at an average free-on-board (FOB) price of US$ 100/m³. In other areas production is probably small and for local consumption only.

Properties

Cerbera yields a lightweight to medium-weight timber with a density of 320-610 kg/m³at 15% moisture content. Heartwood white to pale yellow-brown, not demarcated from the white sapwood; grain straight to slightly interlocked; texture fine and uneven because of the banded parenchyma; wood with darker streaks on radial and tangential surfaces. Growth rings distinct, indicated by marginal parenchyma; vessels moderately small to medium-sized, tending to be radially aligned, mostly in radial multiples of 2-7(-12) and clusters, open; wood parenchyma moderately abundant, apotracheal in narrow continuous, concentric bands, distinct to the naked eye; rays very fine to moderately fine, visible with a hand lens, occasionally with radial latex tubes in C. floribunda ; ripple marks absent; axial latex canals present.

Shrinkage upon seasoning is moderate; the wood seasons readily and well. It works easily. The wood is non-durable and resistant to preservative treatment under pressure. The wood is highly susceptible to blue-staining fungi, the sapwood is susceptible to Lyctus .

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

Botany

Evergreen shrubs or small to medium-sized trees up to 30 m tall; bole up to 90 cm in diameter, not buttressed; bark surface irregularly scaly or warty, peeling off in small flakes, light grey to brown or black-grey, inner bark cream to straw-brown or pale yellow-brown with a greenish tinge, exuding abundant white latex. Leaves arranged spirally, clustered at the apices of twigs, glabrous, entire or sinuate with a decurrent base. Inflorescence terminal, cymose, glabrous. Flowers 5-merous; calyx deeply divided or the sepals free; corolla hypocrateriform, white or light red, strongly scented, lobes overlapping to the left in bud; disk absent; anthers lanceolate, contiguous to the style head and with filiform appendages; carpels 2, free, with 4 ovules in each carpel, style-head composed of 2 annular swellings, surmounted by 2 thick appendages. Fruit apocarpous, with a fleshy exocarp, woody endocarp and 1 or 2 seeds. Seed compressed, not winged. Seedling with hypogeal germination; hypocotyl not elongated.

C. manghas develops according to Koriba's architectural tree model, characterized by orthotropic axes which branch to produce initially equivalent modules but one of these subsequently becomes dominant constituting one unit of the sympodial trunk. In Vietnam Cerbera spp. flower from February to October and bear ripe fruits from August to April. In Australia C. manghas flowers and fruits throughout the year. The flowers are pollinated by insects. The fruits are dispersed by water and are quite commonly washed up on the shores.

There used to be considerable confusion about the correct names for C. manghas and C. odollam . As a result, it is often not possible to allot given information to one of these species.

Ecology

Cerbera species are generally associated with water and occur along rivers or streams, in swamp forest and behind mangroves, but may also be found in shrubby savanna or in secondary forest edges. Some species, like C. manghas and C. odollam , are common elements of mangrove swamps and tidal river banks and may root in muddy locations but also in sandy coastal soils. Most species occur at low altitude in primary lowland rain forest, but some may ascend up to 2000 m.

Silviculture Cerbera can be propagated by seed.

Genetic resources and breeding

There is no reason to believe that Cerbera species are vulnerable to genetic erosion.

Prospects

Cerbera trees seldom grow to timber size. The wood might increasingly be used for veneer as it is soft and presumably easy to cut; the streaked figure which may be present may make its use for face veneer attractive.

Literature

40, 120, 151, 163, 209, 267, 300, 304, 340, 348, 350, 402, 436, 438, 464, 710, 723, 861, 883, 974, 1038, 1132, 1221.