Trichospermum (PROSEA)

Plant Resources of South-East Asia Introduction

List of species

Trichospermum Blume

Protologue: Bijdr. fl. Ned. Ind. 2: 56 (1825).

Family: Tiliaceae

Chromosome number: x= unknown; 2n= unknown

Trichospermum comprises about 40 species, 3 of which occur in tropical South America. The other species are found in South-East Asia from Thailand and throughout the Malesian region to Micronesia and the Pacific, eastwards towards Fiji and Samoa. Two species are present in Japan. There is a marked centre of diversity in New Guinea.

The wood of Trichospermum is used for poles in temporary constructions and fencing and for wooden clogs. It has also been used as fuelwood. T. discolor is regarded as promising for the production of pulp and paper and may be suitable for reforestation in areas frequently hit by typhoons. The Philippine species T. involucratum is expected to have considerable potential as a raw material for pulp and paper production and for wood-based panels. In Fiji the endemic but commercial species T. richii (A. Gray) Seemann, locally called "mako", is suitable for panelling, interior trim, furniture, possibly for veneer and low-grade plywood, blockboard, hardboard and as pulpwood.

From the bark of most species rough rope or cordage can be obtained used for binding or rough baskets, but in the Philippines also for clothing, twines, bow strings, fishing lines and sacks, and for temporary partitions. In New Britain the bark has been used as a wall covering for houses. In the Philippines sawdust of T. involucratum is used as a medium to grow mushrooms.

Utilization of the wood of Trichospermum is on a local scale only. That of T. richii is traded commercially.

Trichospermum yields a lightweight hardwood with a density of 140-390 kg/m³at 11% moisture content. Heartwood pale pink to pale reddish-brown, yellow with a pinkish tinge or grey-brown with a yellow tinge, not clearly differentiated from the sapwood; grain usually straight, occasionally slightly to heavily interlocked or sometimes with spiral grain; texture moderately fine and even. Growth rings mostly indistinct; vessels medium-sized to moderately large, solitary and in radial multiples of 2-4(-6), open; parenchyma not abundant, paratracheal vasicentric, just visible with a hand lens; rays of 2 distinct widths, extremely fine to moderately fine, the broader ones just visible to the naked eye; ripple marks present, sometimes irregular, not always distinct.

The wood is very soft and very weak. There is no information on seasoning and working properties of Malesian species, but shrinkage of timber of T. richii is low to moderate. It seasons well without serious degrade and is fairly easy to work, the finish is even but fibrous. Wood of the Malesian species is non-durable, prone to staining, ambrosia beetle attack and dry-wood termites. A debarked piece of T. discolor left for 5 months did not show appreciable attack by borers or fungi.

The average fibre length of T. discolor is 1.5 mm and of T. involucratum 1.1 mm.

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

Small or rarely medium-sized trees up to 25(-33) m tall; bole straight to crooked, branchless for up to 18 m, up to 50(-70) cm in diameter, rarely with low buttresses; bark surface smooth to finely fissured or cracked, sometimes lenticellate, sometimes flaking in long strips, grey or greyish-green to brown, inner bark fibrous, white or straw to orange or reddish-brown. Indumentum of stellate hairs or stellate scales, rarely with simple hairs. Leaves distichous, simple, finely serrate, 3-veined at base, with glands at the base of the petiole; stipules caducous. Flowers in axillary, umbellate cymes, usually in triads, bisexual or unisexual with male and female flowers on different trees or on the same tree, 5-merous; sepals free; petals with a scale at base; stamens many, inserted on the gynandrophore; ovary superior, (1-)2-6-locular with many ovules, style short. Fruit a dehiscent capsule. Seed flattened, with a corona of radial hairs.

Growth of T. javanicum is rapid. Annual increment of T. discolor is high: 5.9-8.9 cm in diameter and 3.9-6.2 m in height during the first 3 years. Trees are reported to flower when they are still very young. In Java T. javanicum flowers from September to May. In Queensland (Australia) flowers and fruits of T. pleiostigma have been collected from August to October. Seeds of T. discolor are collected from October to December and from April to June.

Trichospermum presently includes the South American genus Belotia and the Malesian genus Althoffia .

Trichospermum species occur scattered in primary and secondary, evergreen to deciduous forest, up to 700 m altitude. Several, perhaps all species are pioneers found in forest clearings and as colonizers of waste land.

Silviculture Being a pioneer, Trichospermum should be easily raised from seed. In a germination trial in Peninsular Malaysia, however, the germination rate of seed of T. javanicum was only 2% in 24-34 days. On the other hand, T. involucratum was reported to be easily raised from seed in the Philippines. T. involucratum is easy to manage in plantations as it is hardy and competes successfully with weeds. Moreover, it can be managed on a very short rotation of five years, the age at which trees naturally start to die. Finally, it regenerates from coppice, which may facilitate regeneration after harvesting. In the Philippines T. discolor has been planted at 3-4 m × 3-4 m and has been observed to possess good self-pruning capacity and to develop a straight cylindrical bole.

The prominent pioneer characteristics of Trichospermum species make them less vulnerable to genetic erosion.

As Trichospermum trees grow very fast, have soft wood, a straight-stemmed habit and can be easily regenerated by coppicing, the pulping properties should be further investigated. The Philippine species T. discolor seems particularly promising.

70, 109, 114, 126, 151, 163, 164, 267, 335, 400, 436, 438, 536, 624, 780, 829, 831, 875, 887, 974, 1038, 1039, 1221, 1232.