Strombosia (PROSEA)
Introduction |
Strombosia Blume
- Protologue: Bijdr. fl. Ned. Ind. 17: 1154 (1826).
- Family: Olacaceae
- Chromosome number: x= unknown; 2n= unknown
Vernacular names
- Dedali (trade name): S. javanica .
- Kamap (trade name): S. ceylanica and S. philippinensis .
Origin and geographic distribution
Strombosia comprises about 12 species, about 9 of which occur in tropical Africa and 3 others in Asia from Sri Lanka, south India and Burma (Myanmar) to Thailand, Peninsular Malaysia, Sumatra, Java, Borneo, the Philippines and the Moluccas. All 3 Asian species are present within the Malesian region.
Uses
The heavier timber of Strombosia , "kamap", is used for temporary construction, flooring, pallets and posts. S. philippinensis is reported as being suitable for making shuttles and bobbins, and the young stem could be made into walking-sticks.
The lighter timber of Strombosia , "dedali", is used for general utility purposes, local house building, medium-heavy construction under cover, interior finish, cabinet work, packing cases and in Indonesia for bent-work like badminton rackets. It is also used for the production of veneer and plywood.
The leaves of S. javanica are eaten raw or cooked and taste like groundnuts. The pulp of the fruits of S. philippinensis is eaten raw.
Production and international trade
As supplies are generally small, Strombosia wood is used on a local scale only.
Properties
S. ceylanica and S. philippinensis ("kamap") yield a heavy hardwood with a density of (635-)790-1220 kg/m3at 15% moisture content, S. philippinensis being the harder and heavier of the two. Heartwood chocolate-brown or purple-brown, sharply demarcated from the about 4 cm wide, pale yellow-brown sapwood which may be much wider in small trees; grain straight ( S. philippinensis ) or interlocked ( S. ceylanica ); texture very fine to moderately fine and even; wood lustrous. Growth rings indistinct; vessels moderately small, solitary and in radial multiples of 2-5, tyloses common; parenchyma moderately abundant, apotracheal diffuse to diffuse-in-aggregates, indistinct even with a hand lens; rays very fine to moderately fine; ripple marks absent.
Kamap wood is subject to checking when seasoned in large pieces. It is hard to exceptionally hard. The wood is not difficult to work for such a hard wood and it takes a high polish. After pre-heating, 1.25 mm thick veneer can be produced without difficulty, but it is difficult to obtain thicker veneer. It is moderately durable to very durable; in a graveyard test in the Philippines the average service life of test stakes of S. philippinensis was 7 years and 8 months. The heartwood of S. philippinensis is very resistant to dry-wood termites, its sapwood is non-susceptible to Lyctus .
S. javanica ("dedali") yields a medium-weight hardwood with a density of 540-770 kg/m3at 15% moisture content. Heartwood pale yellow with an olive-brown tinge, darkening to pale orange-brown, moderately sharply differentiated from the paler sapwood, 2-15 cm wide; grain straight or interlocked; texture fine to moderately fine and even. Growth rings indistinct; vessels moderately small, in radial multiples of 2-8, occasionally solitary, usually open; parenchyma abundant, apotracheal diffuse and diffuse-in-aggregates; rays very fine; ripple marks absent.
Shrinkage upon air drying is moderate to high. The wood seasons very slowly: boards 13 mm and 38 mm thick take respectively about 7 and 12 months to air dry. Degrade upon air drying is a moderate amount of cupping, twisting, end-checking and surface-checking, and the wood is very susceptible to insect attack during seasoning. The wood is soft to moderately hard and of moderate strength. It is easy to saw and plane although the radial surface is slightly rough due to picking up of the grain. The wood is moderately durable when exposed to the weather or in contact with the ground, which is remarkable for a moderately soft wood. The wood is resistant to impregnation.
The gross energy value of the sapwood of S. ceylanica is about 21 205 kJ/kg.
See also the tables on microscopic wood anatomy and wood properties.
Botany
Evergreen, small to medium-sized trees up to 30(-40) m tall, rarely shrubs; bole columnar, sometimes knobbly, up to 70(-120) cm in diameter, sometimes twisted or fluted or rarely with steep buttresses; bark surface shallowly, irregularly fissured or cracked, peeling off with scroll-shaped flakes, yellowish-grey to reddish-brown or purple-brown, inner bark firm, cream with yellow to orange-brown flecks; crown dense, compact. Young twigs often zigzag. Leaves arranged spirally, sometimes almost distichous, simple, entire, exstipulate. Flowers in an axillary, short-peduncled cyme or sessile fascicle; calyx a shallow, 5-lobed cup, accrescent; petals (4-)5, free, greenish, hairy inside; stamens (4-)5, filaments largely adnate to the petals; disk (3-)5-lobed; ovary initially superior, finally partly inferior, 3-5(-6)-locular below, 1-locular above, with 3-5(-6) ovules, style short to elongate, stigma obscurely 3-5(-6)-lobed. Fruit a 1-seeded drupe crowned by the persistent calyx and style base, green ripening cream. Seed with abundant, oily endosperm. Seedling with hypogeal germination; cotyledons not emergent; hypocotyl elongated; first few leaves scale-like and decussate, subsequent leaves arranged spirally on the orthotropic leader, but alternate-distichous on the branches.
An individual 24-year-old S. javanica tree in the arboretum of the Forest Research Institute Malaysia, Kepong measured 16 m in height and 23 cm in diameter; generally, growth is considered to be slow. The crown is monopodial or ultimately sympodial. S. philippinensis flowers from April to May and bears fruits from June to August. S. javanica is reported to flower at irregular intervals. The fleshy pericarp and large seeds suggest dispersal by animals, mainly monkeys and birds.
Ecology
Strombosia is found scattered but may occur locally common in primary, evergreen, lowland rain forest, from near the sea to 800(-1000) m altitude.
Silviculture Strombosia can be propagated by seed. S. ceylanica has about 405 dry seeds/kg, S. javanica 235 dry seeds/kg. Pyrenes of S. javanica show complete germination in 64-185 days. S. javanica is shade-tolerant.
Genetic resources and breeding
Strombosia is rather common and does not seem endangered.
Prospects
It is unlikely that Strombosia timber will be increasingly used. Its use for specialty purposes related to its strong and durable wood will remain locally important.
Literature
151, 163, 235, 238, 260, 261, 267, 319, 320, 341, 354, 387, 406, 436, 464, 632, 677, 678, 740, 741, 780, 804, 829, 831, 832, 861, 933, 934, 955, 1023, 1048, 1221, 1239, 1242, 1268.