Prainea (PROSEA)
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Introduction |
Prainea King ex Hook. f.
- Protologue: Fl. Brit. India 5: 546 (1888).
- Family: Moraceae
- Chromosome number: x= unknown; 2n= unknown
Origin and geographic distribution
Prainea comprises 4 species which are found in Peninsular Malaysia, Sumatra, Borneo, the Moluccas and New Guinea.
Uses
The hard and heavy wood of Prainea is used for posts and beams in house and bridge building.
The fleshy perianth surrounding the fruit is edible.
Production and international trade
The wood of Prainea is used on a local scale only.
Properties
Prainea yields a medium-weight to heavy hardwood with a density of 460-745 kg/m3 for P. papuana and 770-930 kg/m3 for P. limpato at 15% moisture content. Heartwood olive-yellow-brown when fresh, darkening upon exposure to dark olive-brown, sharply demarcated from the pale yellow, up to 8 cm wide sapwood; grain shallowly interlocked; texture moderately fine and even; wood with ribbon figure visible as narrow stripes on radial surface due to alternating grain. Growth rings distinct to indistinct, boundary indicated by marginal parenchyma, visible to the naked eye; vessels medium-sized, solitary and in radial multiples of 2(-3), tending to oblique arrangement, tyloses abundant; parenchyma moderately abundant to abundant, apotracheal in marginal or seemingly marginal bands, and paratracheal aliform, tending to confluent connecting 2 to several vessels laterally; rays moderately fine to medium-sized, distinct to the naked eye on transverse surface; ripple marks absent.
Shrinkage upon seasoning is low, with only slight checking and warping. The wood is hard to very hard, strong (P. limpato) or moderately strong (P. papuana). It is usually difficult to work and to plane. The wood of P. limpato is very durable, that of P. papuana slightly durable when exposed to the weather or in contact with the ground. The sapwood is considered to be susceptible to Lyctus.
See also the table on microscopic wood anatomy.
Botany
- Dioecious, small to fairly large trees up to 40 m tall; bole up to 90 cm in diameter, buttresses present; bark surface cracking to scaly and peeling off in flakes, grey-brown to red-brown, inner bark orange-yellow, exuding white latex.
- Leaves alternate and distichous, simple, entire; stipules lateral or interpetiolar.
- Inflorescence pedunculate, solitary or paired in leaf axils, unisexual, capitate, with globose heads, without an involucre; interfloral bracts many, peltate, clavate or spatulate; perianths free.
- Male flowers numerous; perianth tubular, bilobed or perforate above; stamen 1; pistillode absent. Female flowers 20-100 per head; perianth tubular, clavate, 2-4-lobed or merely perforate above; ovary superior, 1-locular with a single ovule, style bifid.
- Fruit 1-20 per head; perianth greatly enlarged and fleshy, subglobose to ellipsoid.
- Seed large, without endosperm.
- Seedling with hypogeal germination; cotyledons not emergent; hypocotyl not elongated; epicotyl with a few scale leaves followed by alternately arranged normal leaves.
Ecology
Timber-yielding Prainea species are found in lowland, evergreen rain forest, sometimes on the edges of peat-swamps or floodplains, up to 800 m altitude, P. papuana occurs up to 1200 m altitude.
Silviculture
Prainea can be propagated by seed. The germination rate of seeds of P. limpato is 75-95% in 13-27 days.
Genetic resources and breeding
There are no records of ex situ conservation of Prainea species.
Prospects
As long as supplies are sufficient the hard and durable timber of P. limpato will remain to be used locally in heavy constructional works.
Literature
261, 267, 436, 490, 829, 831, 861, 1221, 1232.
Selection of species
Authors
E. Boer (general part),
M.S.M. Sosef (general part, selection of species)
