Broussonetia (PROSEA)

Plant Resources of South-East Asia Introduction

List of species

Broussonetia L'Hér. ex Vent.

Protologue: Tabl. règn. vég. 3: 547 (1799).

Family: Moraceae

Chromosome number: x= 13;B. papyrifera(L.) L'Hér. ex Vent.: 2n= 26,B. kazinokiSiebold: 2n= 26, 39

Vernacular names

• Indonesia: bohulilambaji, ragantulu (Sulawesi)
• Philippines: himbabao, malambingan (Filipino), babayan (Tagalog).

Origin and geographic distribution

Broussonetia comprises about 7 species occurring from India and Sri Lanka to Indo-China, China, Japan, Taiwan, Thailand, and throughout the Malesian region. Only 1 species yields timber: B. luzonica (Blanco) Bureau (synonyms: Allaeanthus luzonicus (Blanco) Fern.-Vill., A. glaber Warb.) which occurs in the Philippines and Sulawesi and has been introduced into Polynesia.

Uses

The wood of Broussonetia is used for panelling, furniture and cabinet work, gunstocks, musical instruments, butchers' blocks, and especially for boat planking.

Trees have been planted in southern Luzon to shade "abaca" ( Musa textilis Nee). Young leaves and flowers can be eaten as a vegetable. The fibrous bark yields inferior rope.

Production and international trade

The wood of Broussonetia is used on a local scale only.

Properties

B. luzonica yields a medium-weight hardwood with a density of 495-630 kg/m³at 15% moisture content. Heartwood variably coloured with grey, red and fawn shades on radial surface, not sharply demarcated from the pale sapwood; grain interlocked; texture moderately fine; wood lustrous and with distinct ribbon figure on radial surface. Growth rings indistinct; vessels medium-sized, some moderately large, mostly solitary, occasionally in radial multiples of 2(-4), tyloses present but not abundant; parenchyma paratracheal and clearly vasicentric to slightly aliform and in wide irregularly spaced apotracheal bands; rays medium-sized, visible to the naked eye; ripple marks absent.

The wood seasons well. It is moderately soft, but fairly strong and easy to work. The wood is not resistant to fungal attacks, the heartwood is resistant to dry-wood termites. The sapwood is susceptible to Lyctus .

See also the table on microscopic wood anatomy.

Botany

A deciduous, dioecious, small to medium-sized tree up to 25 m tall; bole up to 60 cm in diameter; bark surface slightly fissured, pale grey, inner bark fibrous. Leaves distichous, simple, entire, tomentose below; stipules membranous, long pointed. Inflorescence axillary. Male flowers in a dense raceme or spike, sessile; interfloral bracts stalked; perianth 4-lobed, white villous; stamens 4; pistillode minute. Female flowers in a globose head; perianth utricular, with 4 small lobes or teeth; ovary superior, sessile, 1-locular with a single ovule, style 1, filiform. Fruit a globose syncarp with numerous seeds, endocarp crustaceous to woody. Seedling with epigeal germination; cotyledons emergent; hypocotyl elongated.

Seedling growth is very rapid. In the Philippines seedlings 30 cm tall showed average diameter and height increments of 4.3 cm and 4.9 m, respectively, in 14 months. Maximum diameter and height increments in the same experiment were 6 cm and 7.3 m, respectively.

B. papyrifera , the "paper mulberry", is a well-known source of pulp in South-East Asia.

Ecology

B. luzonica occurs in secondary forest, forest edges and thickets, up to 1000 m altitude. It prefers well-drained and sometimes rocky locations.

Silviculture In the Philippines the survival rate of planted B. luzonica was about 85%. B. papyrifera was planted in a trial in Indonesia, but it developed a crooked habit. The latter easily produces root suckers and coppices profusely and for this reason has become a pest in some areas in India.

Genetic resources and breeding

In the Philippines B. luzonica has been depleted due to destruction of its habitat.

Prospects

Because of the very limited supply and its depletion, the use of the wood of B. luzonica is likely to decrease.

Literature

150, 205, 235, 238, 427, 780, 861, 934, 1254.

E. Boer & M.S.M. Sosef