Glochidion (PROSEA Timbers)
Introduction |
Glochidion J.R. Forster & J.G. Forster
- Protologue: Charact. gen. pl.: pl. 113, t. 57 (1775).
- Family: Euphorbiaceae
- Chromosome number: x= 13;G. arborescens,G. velutinumWight:n= 26
Vernacular names
- Glochidion, pin-flower tree (En)
- Indonesia: dempul (Javanese), ki pare, ki timbel (Sundanese)
- Malaysia: obar nasi (Sabah), ubah, ubar (Peninsular)
- Philippines: bagna, salanisin (Filipino). Singapore: ubah merah
- Thailand: khrai mot
- Vietnam: bọt ếch, sóc.
Origin and geographic distribution
Glochidion comprises about 280 species, most of which occur in the Old World tropics from India to Burma (Myanmar), Indo-China, southern China, Thailand, throughout the Malesian region, northern Australia and Polynesia. Few species are found in tropical America and Madagascar. Malesia harbours over 100 species.
Uses
The wood of Glochidion is used to build native and temporary houses, mainly as poles and rafters, and for tool handles. In New Guinea it is used for light framing, flooring, moulding, interior trim and utility furniture. The trees yield a good "hot" fuelwood and the boles have been used in mushroom cultivation.
The bark of several species has been used to tan fishing nets and also for fishing net floats. The leaves of several species are applied medicinally, e.g. in a decoction to treat stomach-ache, against diarrhoea and worms. The roots of G. obscurum have been applied similarly against stomach-ache. Young shoots of G. borneense are eaten as a vegetable.
Production and international trade
Because the timber of Glochidion is generally of small size and supplies are limited, it is used mainly on a local scale. In 1996 Papua New Guinea exported only 34 m3of Glochidion logs at an average free-on-board (FOB) price of US$ 99/m3.
Properties
Glochidion yields a lightweight to medium-weight hardwood with a density of 440-890 kg/m3at 15% moisture content. Heartwood pale purple-grey-brown or red-brown, not clearly differentiated from the pale brown sapwood; grain straight; texture moderately fine and even. Growth rings indistinct, occasionally visible; vessels moderately small to medium-sized, mostly in radial multiples of 2-4(-more), occasional white deposits present; parenchyma sparse, paratracheal vasicentric, barely visible even with a hand lens; rays medium-sized, fairly conspicuous on radial surface; ripple marks absent. Intraspecific variation in wood anatomical characters is very large in Glochidion .
Shrinkage upon seasoning is moderate to very high, especially in the tangential direction. The wood is moderately hard and of low to medium strength. It is non-durable to moderately durable and pressure treatment is difficult. The sapwood is resistant to Lyctus .
See also the tables on microscopic wood anatomy and wood properties.
Botany
Monoecious shrubs or small to occasionally medium-sized trees rarely up to 30 m tall; bole straight or sinuous, sometimes short, dividing low, up to 50(-70) cm in diameter, without buttresses; bark surface smooth to fissured or flaking, dark brown or grey-brown to blackish, inner bark soft, pale brown to purple or reddish, with a watery exudate. Leaves alternate, distichous, displayed in long sprays, simple, entire, often asymmetrical at base, with short petioles; stipules usually persistent. Flowers unisexual, in an axillary, unisexual or bisexual, small cluster below the leaves; sepals 4-6; petals absent; disk absent. Male flower with 3-8 stamens, filaments united into a column; pistillode absent. Female flower with a superior, 3-9-locular ovary with 2 ovules per cell, styles connate or rarely free, entire. Fruit a woody capsule, lobed or ribbed, splitting from the base upward, with persistent sepals and style. Seed with fleshy, red or orange sarcotesta. Seedling with epigeal germination; cotyledons emergent, leafy; hypocotyl elongated; leaves alternate or arranged spirally, conduplicate.
In secondary vegetation the mean annual diameter increment of G. philippicum for the diameter class 5-10 cm was 2 cm, which is very high. Trees develop according to Cook's architectural model, characterized by a monopodial trunk along which branches resembling compound leaves are produced continuously. Glochidion flowers throughout or several times a year. Pollination is by insects; seed dispersal presumably by birds.
Glochidion is closely related to and sometimes confused with Phyllanthus . Unlike the latter it has no disk glands but does have fused styles and colourful seeds.
Ecology
Glochidion species are very common and characteristic elements of secondary forest and colonize cleared land, but also occur scattered in primary rain forest. They can be found in well-drained as well as swampy locations, from the lowland up to 2750 m altitude; most species show a comparatively wide altitudinal range.
Silviculture Glochidion can be propagated by seed and by cuttings; the latter have been used for the establishment of Glochidion as understorey crop in teak plantations. Seeds of G. obscurum still in their sarcotesta have about 60% germination in 12-49 days, whereas those of G. sericeum germinate for about 25% in 26-98 days. A top-boring Rhodoneura sp. has been observed on Glochidion sp., but damage seems to have been limited. Trees are not fire-resistant.
Genetic resources and breeding
There are no records of Glochidion in germplasm banks. As most species occur commonly, they are unlikely to be endangered.
Prospects
Those Glochidion species which are pioneers may prove useful in erosion control, but they have no outstanding wood qualities.
Literature
26, 27, 28, 30, 32, 33, 34, 36, 70, 101, 162, 163, 209, 238, 260, 267, 300, 348, 402, 436, 464, 484, 543, 829, 831, 860, 861, 974, 1038, 1195, 1221, 1222, 1242.