Archidendron (PROSEA)

Plant Resources of South-East Asia Introduction

List of species

Archidendron F. v. Mueller

Protologue: Fragm. 5: 59 (1865).

Family: Leguminosae

Chromosome number: x= 13;A. clypearia:n= 13

Vernacular names

• Indonesia: jengkol (general)
• Malaysia: keredas (Peninsular).

Origin and geographic distribution

Archidendron comprises 94 species and occurs from Sri Lanka and India to Indo-China, southern China, Taiwan, Burma (Myanmar), Thailand, throughout the Malesian region, Micronesia, the Solomon Islands and north-eastern and eastern Australia. There are 2 centres of speciation, one in Indo-China, extending to western Malesia, the other in New Guinea. Within Malesia 62 species are found.

Uses

The wood of Archidendron is used for light construction, interior joinery, furniture and cabinet work, canoes, paddles, fencing, household utensils, knife handles, weapon sheaths, boxes and coffins. It is also used as fuel.

A. ellipticum has been used as cover crop in forest plantations in Indonesia. The seeds of A. jiringa and, occasionally, also those of A. bubalinum and A. microcarpum are used to flavour food. They are also applied traditionally as a diuretic, but are poisonous when eaten in large amounts. Young seeds are often eaten raw. The pods of A. jiringa have been used to obtain a purple dye for silk; they are still a source of shampoo. In Borneo a black dye is produced from the bark and leaves; the bark is also used with mud for matting. The ash of old leaves is a remedy against pain in the chest and for itch, that of young leaves is applied to wounds. A poultice of leaves of A. clypearia and A. microcarpum is a traditional medicine to treat chickenpox, smallpox, sore legs, swellings and coughs. The bark of A. clypearia yields tannin for nets and to treat scabies, that of A. bubalinum is used as a febrifuge. The bark of A. ellipticum and A. jiringa is also applied as fish poison.

Production and international trade

The wood of Archidendron is used on a local scale only. Seeds of A. jiringa are found regularly in local markets in Malaysia and Indonesia.

Properties

Archidendron yields a lightweight to medium-weight hardwood with a density of 350-860 kg/m³at 15% moisture content. Heartwood whitish with a pink tinge, yellowish or pale red-brown, darkening to deep brown with age, clearly demarcated from the up to 3 cm wide white, greyish-white, pale yellow or pale brown sapwood; grain straight, slightly interlocked or wavy; texture moderately coarse but even; wood lustrous. Growth rings usually indistinct, but distinct in A. jiringa , boundary indicated by marginal parenchyma, occasionally by darker-coloured latewood; vessels medium-sized to moderately large, mostly solitary but also in radial multiples of 2-3, vessels with white, yellow or white deposits conspicuous on longitudinal surfaces; parenchyma moderately abundant, paratracheal vasicentric, aliform, occasionally confluent forming broad bands, and apotracheal in marginal or seemingly marginal bands, diffuse very sparsely present; rays moderately fine; ripple marks absent.

The wood is moderately hard. It is easy to saw and work to a smooth finish, but requires considerable filling if it is to be polished. The wood is only moderately durable when exposed to the weather or in contact with the ground. The sapwood is susceptible to Lyctus and to stain.

See also the table on microscopic wood anatomy.

Botany

Usually evergreen, unarmed shrubs or small to medium-sized or rarely fairly large trees up to 30(-42) m tall; bole straight to rather crooked, short to branchless for up to 20 m, up to 90(-150) cm in diameter, occasionally with short buttresses; bark surface smooth to closely fissured, lenticellate, brown to pale grey, inner bark greenish-yellow to purplish-red. Leaves arranged spirally, bipinnate; rachis and pinnae with extrafloral nectaries; leaflets opposite, rarely alternate or 1-foliolate; stipules sometimes present. Inflorescence composed of a pedunculate glomerule, umbel, corymb, or raceme which is simple or compound in an axillary, terminal or cauliflorous panicle. Flowers bisexual or sometimes unisexual, 5-merous, sometimes 3-merous; both calyx and corolla connate, valvate; stamens many, staminal tube united with corolla tube at base, long exserted; ovaries 1-15 per flower, superior, sessile or stalked, 1-locular with many ovules. Fruit a coriaceous to woody, straight to spirally twisted, flat or terete, sometimes segmented pod, dehiscing along 1 or both sutures, often reddish or purple. Seed ellipsoid, flattened, without pleurogram. Seedling with hypogeal or semihypogeal germination; cotyledons not emergent, fleshy; hypocotyl sometimes slightly elongated; first leaf or first few leaves scale-like, subsequent ones bipinnate.

All three Philippine timber-yielding species have root nodules. Many species have been observed flowering and fruiting almost throughout the year. Flowers of A. jiringa open in the evening and are pollinated by moths and other insects. Seeds are eaten by squirrels, monkeys, and probably birds which disperse them.

Archidendron belongs to the subfamily Mimosoideae and the tribe Ingeae . Within the tribe generic limits are uncertain and have been disputed. Species formerly included in e.g. Pithecellobium sect. Clypearia Benth., and the genera Abarema sensu Kosterm., Cylindrokelupha Kosterm., Paraalbizzia Kosterm. and Zygia sensu Kosterm. have been transferred to Archidendron . Some species of Archidendron and Pithecellobium have been transferred to the small genus Archidendropsis ; Archidendropsis spicata (Verdc.) I.C. Nielsen from New Guinea, locally known as "koboar", is used to build canoes and is of particular interest as a lesser-known timber. Archidendron is the only genus within the family with more than one ovary per flower.

Ecology

Timber-yielding Archidendron species occur in primary and secondary, lowland to lower montane, evergreen rain forest, up to 1650 m altitude. They occur in swamps and riverine forest, but also on well-drained locations, and on a wide variety of soils including clay, laterite, sand and limestone soils.

Silviculture Archidendron can easily be propagated by seed. When stored in airtight containers at ambient temperature, seeds of A. globosum remain 100% viable for 4 months; viability rapidly decreases to about 60% and 25% for seeds stored for 5 and 6 months, respectively, whereas seeds stored for 7 months or more is no longer viable. Seeds of A. clypearia , A. ellipticum and A. microcarpum have 85-100% germination in 6-40 days, germination of A. bubalinum seeds starts later and is almost complete in 35-50 days.

Genetic resources and breeding

Logging of Archidendron is virtually non-existent and is not likely to cause genetic erosion.

Prospects

Some Archidendron species may have some potential for the manufacture of small household items, but more research needs to be done first on their physical and chemical wood properties.

Literature

12, 75, 151, 163, 198, 238, 253, 260, 267, 304, 341, 343, 366, 436, 829, 831, 840, 861, 974, 1015, 1038, 1039, 1163, 1169, 1221.