Bouea (PROSEA)

Plant Resources of South-East Asia Introduction

List of species

Bouea Meisn.

Protologue: Pl. vasc. gen.: tab. diagn. 75, comm. 55 (1837).

Family: Anacardiaceae

Chromosome number: x= unknown; 2n= unknown

• Plum mango (En)
• Malaysia: kundang (general), merapoh (Peninsular).

Bouea comprises 3 species and is found in Burma (Myanmar), the Andaman Islands, Indo-China, southern China, Thailand, Peninsular Malaysia, Sumatra, Java and Borneo. One species is a rare endemic of Vietnam, the other two are more widespread and cultivated within their natural area of distribution, B. macrophylla also in Ambon.

The dark brown centre of the heartwood of Bouea is sought after in Peninsular Malaysia for cabinet work and tobacco pipes. The wood has also been used in house building (e.g. joists, rafters), for scabbards, tool handles and rice pounders. In Indo-China the frequently occurring burrs on the bole are used for joinery.

The dense crowns render Bouea an attractive ornamental shade tree. Fruits are eaten raw, steamed or made into an excellent compote and young fruits are sometimes pickled or made into preserve. The young leaves of B. macrophylla can be eaten raw, e.g. with rice.

Utilization of the wood of Bouea is very limited and on a local scale only.

Bouea yields a medium-weight hardwood with a density of 675-895 kg/m³at 15% moisture content, but a density of 910-1130 kg/m³was recorded for two specimens of B. oppositifolia from Indonesia, which implies that it is a heavy hardwood. Heartwood pale brown with a pinkish tinge, reportedly with a core of dark brown wood with black streaks in B. macrophylla , sapwood pale brown with a red tinge, grey-brown or yellowish-brown usually not clearly differentiated from heartwood; it has been stated that the sapwood is up to 7 cm wide; grain straight or interlocked; texture rather coarse but even; wood with attractive zig-zag figure due to darker parenchyma. Growth rings occasionally distinct macroscopically due to wider spacing of banded parenchyma; vessels medium-sized to moderately large, mainly solitary but also in radial multiples of 2-3, tyloses rare; parenchyma moderately abundant, paratracheal vasicentric to occasionally aliform and apotracheal in wide regularly to irregularly spaced bands, the apotracheal parenchyma visible to the naked eye; rays very fine to moderately fine, visible with a hand lens; ripple marks absent.

Wood samples generally season well without defects. The wood is hard and strong. The heartwood is reputed to be durable, but the sapwood is susceptible to Lyctus .

See also the table on microscopic wood anatomy.

Medium-sized to fairly large trees up to 36 m tall; bole up to 80 cm in diameter, not buttressed; bark surface smooth to cracked or finely fissured, dark grey to reddish-brown or pale greyish-brown, inner bark finely fibrous, red or reddish-brown, with gummy exudate; crown very dense. Young twigs often 4-angular; buds pointed and prominent. Leaves decussate, simple, entire, with a resinous smell when crushed. Flowers male or bisexual, small, in an axillary or rarely terminal panicle, 3-5-merous, whitish or pale yellow to yellowish-green; calyx lobed; petals keeled; disk present; ovary superior, 1-locular with 1 ovule, style short, stigma round and flat, sometimes 2-3-grooved. Fruit a drupe. Seed with testa adherent to the endocarp. Seedling with semi-hypogeal germination; cotyledons not or only slightly emergent, fleshy; hypocotyl not elongated; leaves conduplicate.

Growth of B. oppositifolia in Burma (Myanmar) is slow. B. macrophylla is evergreen, B. oppositifolia is deciduous. The inflorescences appear together with the new leaves. In Indonesia B. macrophylla flowers from June-November and fruits from March-June. The fruits of B. macrophylla are dispersed by bats.

Bouea is the only genus within the family Anacardiaceae having decussate leaves. It may be mistaken for genera of other families like Garcinia , Syzygium , Olea or Memecylon , but can be distinguished by the resinous smell of the broken twigs or crushed leaves and the pointed buds.

B. macrophylla occurs naturally in evergreen lowland rain forest up to 300 m altitude; when cultivated it is found up to about 850 m. It thrives on light, fertile soils. B. oppositifolia is found in evergreen to deciduous lowland rain forest including sandy coastal forest and peat-swamp forest, up to 700 m altitude.

Silviculture Bouea can be grown from seed, but B. macrophylla is also propagated by marcotting or grafting. Seeds rapidly lose their viability and should be sown immediately after collecting. Fruits germinate more slowly and more erratically than stones, which always show 100% germination. Stones of B. macrophylla took 11-22 days to germinate and B. oppositifolia stones took 19-33(-57) days. B. macrophylla needs shade for several months after planting.

B. macrophylla includes several fruit varieties that differ in sweetness. A germplasm collection of B. oppositifolia is maintained in Thailand.

The use of Bouea may increase because it may serve as a multipurpose tree providing timber, fruit and shade.

162, 163, 209, 267, 341, 343, 371, 436, 825, 829, 831, 861, 1038, 1048, 1123, 1164, 1221, 1242.