Hydnocarpus (PROSEA Timbers)
- Protologue: Fruct. sem. pl. 1: 288, t. 60, f. 3 (1788).
- Family: Flacourtiaceae
- Chromosome number: x= 12; H. anthelmintica: 2n= 24, H. ilicifolia King: 2n= 22, H. kurzii(King) Warb.: 2n= 24
- Senumpul (trade name)
- Malaysia: karpus (Sabah), setumpol (Peninsular)
- Burma (Myanmar): kalaw
- Thailand: krabao.
Origin and geographic distribution
Hydnocarpus comprises about 40 species occurring in Sri Lanka, south-western India and Assam, Burma (Myanmar), Indo-China, southern China, Thailand (7 species), Peninsular Malaysia (12), Sumatra (12), Java (2), Borneo (17), the Philippines (5) and Sulawesi (2).
The wood of Hydnocarpus is used for local house building (poles), temporary heavy construction, posts, fences, interior finishing, panelling and door and window frames. When available in sufficient quantities it may be suitable for furniture, flooring, mouldings and partitioning. It is also suitable for mathematical instruments, tripods and packing cases. Locally, it has been used as firewood.
The seeds of several species (notably H. anthelmintica and H. kurzii) yield an oil that is well-known as a cure for leprosy and skin diseases. In Cambodia this oil has also been used for illumination and applied for soap-making. The fibrous bark is made into cordage. The pulp of the fruits is edible. Occasionally, trees are planted as an ornamental.
Production and international trade
There are no specific records of trade of Hydnocarpus timber. It is most likely used on a local scale only, or traded in mixed consignments of medium-weight hardwood.
Hydnocarpus yields a medium-weight to heavy hardwood with a density of 690-950 kg/m3at 15% moisture content. Heartwood pale yellow or yellow-brown, not clearly demarcated from the sapwood; grain straight or interlocked, sometimes deeply interlocked; texture fine or moderately fine and even. Growth rings usually indistinct; vessels very small to medium-sized, solitary or in radial multiples of 2-4, markedly angular, occasionally with pale deposits and tyloses; parenchyma absent; rays very fine to moderately fine, visible to the naked eye; ripple marks absent.
The wood is difficult to season and liable to check and split, but it is also reported to season well without serious defects. The wood is hard, but works well with hand machine tools. It is probably moderately durable under exposed conditions, but has also been reported as non-durable, even under cover. The wood is susceptible to termite attack. The average fibre length of H. kunstleri is 3.49 mm.
See also the table on microscopic wood anatomy.
- Evergreen, dioecious or occasionally monoecious shrubs or small to medium-sized or rarely large trees up to 25(-50) m tall; bole up to 85 cm in diameter, sometimes with low buttresses; bark surface usually smooth, sometimes cracking and scaly, pale brown to greyish, inner bark granular to fibrous, cream or sometimes with orange to yellow-brown spots or mottles.
- Leaves alternate, simple, entire or serrate, slightly asymmetrical at base; stipules early caducous.
- Flowers unisexual, 4-5-merous; sepals free or rarely slightly connate at base, imbricate; petals with a mostly densely pilose scale at base inside. Male flowers in an axillary cyme or rarely in a raceme-like cauliflorous or ramiflorous panicle; stamens 5-many. Female flowers 1-3 together; ovary superior, unilocular with many ovules, stigma sessile and with 3-5 spreading branches.
- Fruit an indehiscent, globose drupe with closely packed seeds.
- Seed with a membranous aril.
- Seedling with epigeal germination; cotyledons emergent or not, leafy; hypocotyl elongated; all leaves arranged spirally, conduplicate.
Tree architecture of H. anthelmintica is according to Roux's architectural model, characterized by a continuously growing monopodial orthotropic trunk with plagiotropic branches. Flowering is usually once a year, but the period differs per region. Fruit takes a long time to develop; for instance H. woodii fruits take about 7.5 months. Dispersal of the fleshy fruits by animals seems likely, but has to be confirmed by observations. In Java H. alpina Wight, reportedly originating from India and Thailand, has been planted in a trial and after 26 years trees were on average 18 m tall and 21 cm in diameter. It is uncertain whether the trees concerned were the true H. alpina from western India or H. anthelmintica from Thailand. A 45-year-old H. woodii tree in the arboretum of the Forest Research Institute Malaysia, Kepong measured 17 m in height and 40 cm in diameter.
Most timber-producing Hydnocarpus species are found scattered in primary rain forest, in well-drained level locations or on hillsides, on sandy or clayey soils, up to 1000(-1700) m altitude, occasionally in beach forest or rocky outcrops. H. castanea is also found along streams and rivers and in seasonal swamps. H. heterophylla usually occurs on calcareous soils.
Hydnocarpus can be propagated by seed. Ripe fruits are collected and piled in heaps for 3-4 days. The seeds can then be separated from the pulp by washing. Seed of H. kunstleri has 50% germination in 4-8 months and that of H. woodii has about 50% germination in 5 months to over 2 years. Information on silvicultural aspects is scarce, though from Peninsular Malaysia it is reported that H. woodii is considered shade-tolerant and does not reach the upper canopy stratum.
Genetic resources and breeding
Since there are many Hydnocarpus species, potentially important species should be collected and conserved. Further studies are needed to determine their suitability for plantation-grown cultivation.
Increased utilization of Hydnocarpus is unlikely to occur unless plantations are established.
61, 162, 163, 198, 267, 341, 343, 402, 436, 740, 741, 758, 829, 830, 831, 832, 861, 894, 974, 1028, 1038, 1169, 1219, 1221, 1239, 1242.