Symplocos (PROSEA Timbers)

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Plant Resources of South-East Asia
Introduction
List of species


Symplocos Jacq.


Protologue: Enum. syst. pl. 5: 24 (1760).
Family: Symplocaceae
Chromosome number: x= 11;S. cochinchinensis: 2n= 22, 22 + (1-2)B, 24,S. costata,S. fasciculata,S. laeteviridis: 2n= 22,S. lucida:n= 11,S. pendula: 2n= c. 90

Vernacular names

  • Indonesia: jirak (Sundanese), jirek, sasah (Javanese)
  • Philippines: agosip, himamaliu
  • Thailand: mueat
  • Vietnam: dung.

Origin and geographic distribution

Symplocos is a large genus comprising about 250 species and is distributed in tropical and subtropical Asia, to Fiji in western Polynesia, eastern Australia, and in Central and South America, with a few species extending to temperate regions (to Japan and the United States (Virginia)). Fossils have been found in the Lower Eocene in Europe. Approximately 60 species occur in Malesia. Borneo is richest with about 25 species, followed by Peninsular Malaysia, Sumatra and the Philippines, each with about 20 species; other areas in Malesia have much less species. Indo-China and southern China have no less than about 30 species, Thailand slightly less than 20.

Uses

The wood of Symplocos is used for light and temporary construction, posts, turnery, inlay work, furniture, matches and carving. A good-quality kraft paper can be obtained from some species.

The inner bark and leaves of some species are used as a mordant and yellow to red dye in the batik industry. Young leaves are sometimes eaten raw or steamed as a vegetable. Bark and leaves are used in local medicine, e.g. against thrush, biliousness, haemorrhages, diarrhoea, gonorrhoea and eye diseases. Dayak people extract salt from the wood ash of S. odoratissima .

Production and international trade

Symplocos timber is probably used on a local scale only. In West Java bark and leaves of S. odoratissima are traded locally as a medicine as "kayu seriawan" or "kulit seriawan".

Properties

Symplocos yields a lightweight to medium-weight hardwood with a density of 290-850 kg/m3at 15% moisture content. Heartwood white, pale pink-brown or yellow-brown, not clearly differentiated from the sapwood; grain straight, less often interlocked; texture very fine to fine and even; wood of S. adenophylla with watered-silk figure on tangential surface. Growth rings distinct in some species, boundary indicated by a narrow zone of denser tissue and without vessels; vessels very small to moderately small, mostly solitary, occasionally in radial pairs, rarely with tyloses; parenchyma moderately abundant, apotracheal diffuse and diffuse-in-aggregates, visible with a hand lens; rays of two distinct sizes, very fine and medium-sized, the latter visible to the naked eye; ripple marks absent.

The wood is soft to moderately hard and fairly weak. It is moderately durable under cover but non-durable in exposed conditions. The wood is readily attacked by termites; the sapwood is susceptible to Lyctus . The energy value of the oven-dry sapwood is 19 980 kJ/kg.

The plants contain a large amount of aluminium, which is the origin of the action as a mordant. Ethanol extracts of the leaves of S. lucida showed hypoglycaemic and anti-cancer activity.

See also the table on microscopic wood anatomy.

Botany

Evergreen shrubs or small to medium-sized, rarely large trees up to 30(-45) m tall; bole up to 60(-80) cm in diameter; bark often tasting bitter, bark surface often smooth, sometimes flaking, grey or grey-brown, sometimes dark brown, inner bark creamy, orange-brown or yellowish-brown to pinkish, granular or fibrous. Leaves alternate or arranged spirally (rarely pseudoverticillate), simple, often with vesicular or tooth-like glands at margins, pinnately veined, petiolate (rarely almost sessile); stipules absent. Flowers usually in an axillary spike, raceme or panicle, usually bisexual, 3-5-merous; calyx tube very short; corolla sympetalous but often divided nearly to the base, whitish, bluish or purplish; stamens 4-many, connate into a tube or only at the very base and then sometimes in 5 bundles; ovary inferior, 2-5-locular with 2 ovules in each cell, style 1. Fruit a variously shaped drupe with hard stone, crowned by the persistent calyx lobes. Seed with copious endosperm, cotyledons very short and linear. Seedling with epigeal germination; cotyledons emergent, small, linear and green; hypocotyl elongated; first 2 leaves opposite or alternate-spiral.

Growth is continuous or in flushes. Within a given tree all flowers open more or less at the same time. Pollination is probably by insects like bees and bumblebees, but self-pollination already in bud is also suggested. Although birds and bats may sometimes eat the fruits, fruit dispersal is unlikely to be abundant. For some species e.g. S. celastrifolia , dispersal by water has been noticed.

In herbarium material leaves usually have a yellow colour as a result of the aluminium compound reacting with flavonols in the drying leaves.

Symplocos is the only genus of the family Symplocaceae . Two subgenera are distinguished: subgenus Symplocos comprising in Malesia S. henschelii and S. pendula , and subgenus Hopea (L.) C.B. Clarke containing all other species.

Ecology

Symplocos occurs most abundantly in the tropical highlands up to 4000 m altitude, where it is represented by dwarf shrubs, but many species have a fair altitudinal range and are also found in the lowlands. In general, it is a component in mixed, mostly evergreen rain forest. It is usually rather indifferent to soils, and some species even grow on young volcanic soils or limestone.

Silviculture Symplocos can be propagated by seed. For S. fasciculata there are about 13 000 dry fruits/kg, for S. cochinchinensis about 27 500. Sown stones of S. henschelii have about 75% germination in 6-13 months and sown fruits of S. cochinchinensis have only about 15% germination in 4-7 months. In S. cochinchinensis small leaf galls induced by psyllids cause the leaf halves to curve upward. A gall-midge may occasionally infest stems of S. fasciculata and flowers of S. brandisii .

Genetic resources and breeding

It seems that Symplocos is not particularly threatened because it is little used, either for timber or for dye or mordant, and often occurs in more or less inaccessible mountainous locations.

Prospects

It is very unlikely that the utilization of Symplocos timber will increase since local use is hardly known and supplies are limited.

Literature

70, 163, 209, 235, 267, 341, 343, 405, 436, 464, 543, 696, 780, 790, 829, 831, 849, 860, 861, 947, 1039, 1221.