Blumeodendron (PROSEA)

Plant Resources of South-East Asia Introduction

List of species

Blumeodendron (Müll. Arg.) Kurz

Protologue: Journ. As. Soc. Beng. 42: 245 (1873).

Family: Euphorbiaceae

Chromosome number: x= unknown; 2n= unknown

Vernacular names

• Tengkurung (trade name)
• Malaysia: gaham badak (Peninsular, Sabah), medang lempong (Peninsular), merbulan (Peninsular, Sarawak)
• Philippines: lindog (Tagalog).

Origin and geographic distribution

Blumeodendron comprises 6 species and occurs in the Andaman Islands, southern Burma (Myanmar), peninsular Thailand, throughout the Malesian region (except for the Lesser Sunda Islands and Sulawesi) towards the Bismarck Archipelago.

Uses

The wood of Blumeodendron is used for internal construction and shuttering and, when treated, also for fencing and light constructional work. The logs are generally too small for rotary peeling. The wood of B. subrotundifolium yields a good quality charcoal.

The aril of the seed is edible.

Production and international trade

Because the logs are generally small, Blumeodendron wood is used on a local scale only.

Properties

Blumeodendron yields a medium-weight or occasionally heavy hardwood with a density of (430-)510-895 kg/m³at 15% moisture content. Heartwood pale yellow-brown or straw-brown with a slight pink tinge, not clearly differentiated from the sapwood; grain usually straight, sometimes slightly interlocked; texture moderately coarse and even; occasionally with small corewood with black streaks or grey-black with orange streaks. Growth rings generally indistinct, boundaries sometimes visible due to colour differences; vessels medium-sized to moderately large, solitary and in radial multiples of 2-4, tyloses present but not abundant; parenchyma moderately abundant, apotracheal in narrow bands, just visible to the naked eye; rays very fine to moderately fine; ripple marks absent.

Shrinkage upon seasoning is moderate to high. The wood is subject to degrade with moderately severe end-checking, slight cupping, bowing and splitting. During drying it is highly susceptible to sap-stain and insect attack. Air drying of 13 mm and 38 mm thick boards of B. tokbrai takes 3-4 months and 4-5 months respectively. In Malaysia kiln schedule K is recommended. The wood is moderately hard to hard and moderately strong. It is easy to work, plane and bore, with some picking up in planing. Cutting edges blunt moderately rapidly. The wood is non-durable, with an average service life of 1.5 years in a graveyard test in Malaysia. It is easy to treat with preservatives, having an absorption of 80 kg/m³of a 50% creosote and 50% diesel oil mixture when not heated and 240 kg/m³when heated. The wood is susceptible to termite attack. The sapwood is susceptible to Lyctus .

The mean fibre length of B. tokbrai from Indonesia is 1.456 mm.

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

Botany

Dioecious, small to medium-sized or rarely large trees up to 35(-50) m tall; bole usually straight, up to 120 cm but generally 40-50 cm in diameter, sometimes fluted or with small buttresses, occasionally stilt-rooted ( B. tokbrai in peat-swamp forest); bark surface smooth to finely rugose or scaly, grey-white to ochre-fawn or warm orange-brown, inner bark granular to laminate, brown, yellow-brown or pinkish; crown dense. Leaves alternate to subopposite or falsely whorled, simple, entire; petiole long, prominently kneed at both ends; stipules obsolete. Male flowers in an axillary, condensed cyme or false raceme; calyx valvate, 3-4-partite; petals absent; stamens 14-40, with numerous small glands at their bases; pistillode absent. Female flowers in an axillary, short raceme; sepals 3-5; petals absent; disk annular; ovary superior, 2-3-locular with a single ovule in each cell, styles 2, connate at base. Fruit a large, woody, 1-2-seeded capsule on a thickened pedicel. Seedling with epigeal germination; cotyledons not emergent; hypocotyl elongated; first pair of leaves exstipulate, opposite, subsequent ones alternate or arranged spirally.

In Java B. tokbrai has been observed flowering from April to November, B. kurzii almost throughout the year. In Peninsular Malaysia Blumeodendron has been reported flowering and fruiting in mast years.

B. subrotundifolium closely resembles B. kurzii and the two may prove to be conspecific.

Ecology

Blumeodendron species are canopy or subcanopy trees and may be fairly common in primary or sometimes secondary forest, generally at low altitudes, but ascending up to 2700 m altitude. They are found on flat land, on hills and slopes and also in swamp forest. Soil types vary between sandstone, sandy loams, loam and even clayey soils. B. tokbrai is occasionally found in mangrove forest. B. calophyllum is locally common in primary kerangas forest on yellow sandy clay soil.

Silviculture Blumeodendron can be propagated by seed. About 40% of the seeds of B. calophyllum germinate in 58-139 days.

Genetic resources and breeding

As most Blumeodendron species are widespread, they do not seem in immediate danger of genetic erosion or extinction.

Prospects

Because of the generally good quality of the wood of Blumeodendron , its use may increase when similar timbers become more scarce. However, its average small size limits its applicability.

Literature

21, 26, 28, 32, 33, 34, 36, 70, 162, 163, 267, 387, 436, 543, 676, 677, 740, 741, 745, 829, 831, 861, 974, 1195, 1221, 1242.