Engelhardtia (PROSEA)
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Introduction |
Engelhardtia Lesch. ex Blume
- Protologue: Bijdr. fl. Ned. Ind. 10: 528 (1826).
- Family: Juglandaceae
- Chromosome number: x= 16; E. roxburghiana, E. spicata: n= 16
Vernacular names
- Kayu hujan (trade name)
- Malay beam (En)
- Indonesia: ki hujan (Sundanese)
- Malaysia: dungun paya (general), sansanglang, tansanglang (Sarawak)
- Papua New Guinea: engel
- Philippines: lupisan (Filipino)
- Thailand: kha hot (general)
- Vietnam: chẹo.
Origin and geographic distribution
Engelhardtia comprises 12 species, 3 of which occur in Central America and the remainder in the Old World tropics from the western Himalayas and northern India to Burma (Myanmar), Indo-China, southern China, Taiwan, Thailand and throughout the Malesian region. All 9 Asian species are present in Borneo.
Uses
The wood of Engelhardtia is used for light construction under cover (planking, posts), weatherboard, cartwheels, agricultural implements, mouldings, turnery, gunstocks, packing cases and crates, and canoe building. In India the wood has been used for tea boxes and in Burma (Myanmar) for the production of matches. The darker corewood may be used for furniture. The wood is suitable for the production of plywood, and is occasionally used for fuel.
The bark of E. roxburghiana has been used as a fish poison. It repels leeches.
Production and international trade
Supplies of Engelhardtia timber are sometimes fair but use is generally limited and on a local scale only. It is reputed to be commercially traded in Taiwan. Occasionally, small amounts may be exported from Papua New Guinea in mixed consignments of logs.
Properties
Engelhardtia yields a lightweight to medium-weight hardwood with a density of 380-715 kg/m3at 15% moisture content. Heartwood pink-brown to greyish-brown, not clearly differentiated from the whitish, pale grey or pale brown, 3 to over 10 cm wide sapwood; grain straight or interlocked or slightly wavy; texture moderately fine to slightly coarse and even; wood lustrous; corewood up to 30 cm in diameter, black or streaked in some trees. Growth rings sometimes distinct, boundaries indicated by darker-coloured tissue; vessels medium-sized to moderately large, solitary and in radial multiples of 2-3(-6), occasionally also in clusters, usually open, rarely with tyloses; parenchyma moderately abundant, scanty paratracheal and apotracheal in narrow, interrupted bands, sometimes diffuse-in-aggregates, parenchyma indistinct due to lack of contrast with fibres; rays extremely fine or moderately fine; ripple marks absent.
The wood seasons well, although end-splitting and some surface checking have been reported for E. roxburghiana . It is moderately soft to moderately hard, moderately strong and rather tough. It saws easily but planes to a slightly rough surface. Sawing slightly blunts the saw teeth. The wood is non-durable. Graveyard test stakes of E. roxburghiana were destroyed in 3 years. Large or over-mature logs may sometimes be defective. The heartwood of E. spicata is moderately resistant to dry-wood termites. The sapwood is susceptible to Lyctus .
See also the tables on microscopic wood anatomy and wood properties.
Botany
Evergreen or deciduous, monoecious or dioecious, small to medium-sized or occasionally large trees up to 35(-50) m tall; bole straight, cylindrical, or sometimes poorly shaped, branchless for up to 15 m, up to 90(-280) cm in diameter, with buttresses up to 3(-4) m high; bark surface smooth to fissured, peeling off in often papery flakes, pale grey or brown-grey to red-brown, inner bark fibrous, yellow to pinkish or brown. Indumentum of golden yellow glandular scales. Leaves arranged spirally, paripinnate, exstipulate; leaflets 4-17, opposite to subopposite, entire or serrate, asymmetrical at base. Inflorescence an axillary or occasionally terminal panicle of catkins, unisexual. Flowers tiny, fused with a 3-lobed bract; perianth 4-lobed and persistent in fruit. Male flower often with a reduced perianth; stamens 4-13, sessile or on short filaments. Female flower with perianth lobes in 2 whorls and partly connate with the ovary; ovary inferior, 2-carpellate, each carpel 1-locular with a single ovule, style 1 with 2-4 stigmas. Fruit a small, indehiscent, 1-seeded nut attached to the base of the enlarged, dry, prominently veined bract. Seedling with epigeal germination; cotyledons emergent, palmately 4-lobed; hypocotyl elongated; all leaves arranged spirally, simple at first, then 3-foliate, then 5-foliate, and finally paripinnate with a small terminal appendage.
In India the mean annual diameter increment of E. spicata trees of up to 57 years old is 0.7-1.0 cm. Trees are often briefly deciduous and then flower. The inconspicuous flowers suggest pollination is by wind, but the male catkins of E. roxburghiana are reputed to be slightly fragrant and may be pollinated by insects. The winged fruits are adapted to wind dispersal, spinning and tumbling when they fall.
Sterile trees can easily be mistaken for a member of the Sapindaceae because of the similar leaves. Blume originally spelled the generic name as " Engelhardia " which is an orthographic error and should be corrected according to botanical nomenclatural rules, but some authors still use the original spelling. A recent proposal to incorporate E. roxburghiana into the South American genus Alfaroa has not been accepted yet.
Ecology
Engelhardtia is found scattered in evergreen, primary, lowland or montane rain forest to more open bush-savanna vegetation, often on leached acid yellow soils, up to 2000(-2700) m altitude. It occurs on dry land as well as in swamp forest and is a regular constituent of the montane oak-laurel forest. E. spicata locally forms pure stands in East Java and is especially frequent in Casuarina forest. E. rigida may be locally common in New Guinea in lower montane rain forest in association with Castanopsis , Lithocarpus or Nothofagus .
Silviculture Engelhardtia can be propagated by seed. E. spicata has 89 000-123 000 dry nuts without wings/kg and these can be stored in airtight containers for only 2 months. Sown de-winged nuts of E. roxburghiana had about 65% germination in 17-34 days in a germination trial in Peninsular Malaysia. In a trial in Indonesia those of E. spicata showed only 2-15% germination. Nuts should be sown in the shade. Seedlings of E. roxburghiana never survived in the nursery.
Genetic resources and breeding
Several recently described and narrowly defined Engelhardtia species from Borneo are very rare and known from only single collections. Some species may become endangered through destruction of their habitat.
Prospects
No increase in the use of Engelhardtia wood in the near future is foreseen.
Literature
61, 70, 101, 130, 162, 163, 198, 209, 238, 260, 261, 267, 304, 341, 343, 348, 403, 405, 436, 458, 464, 466, 536, 553, 632, 748, 785, 829, 831, 861, 882, 933, 934, 974, 1038, 1221, 1242.
