Gastonia (PROSEA)

Plant Resources of South-East Asia Introduction

List of species

Gastonia Comm. ex Lamk

Protologue: Encycl. 2: 610 (1786).

Family: Araliaceae

Chromosome number: x= unknown; 2n= unknown

Vernacular names

• Indonesia: amoriga (Manikiong, Irian Jaya), jak (Karoon, Irian Jaya), tuyu (Mooi, Irian Jaya).

Origin and geographic distribution

Gastonia comprises about 13 species occurring in East Africa, Madagascar, the Seychelles and Mascarenes, the Malesian region (in the Philippines only present on Palawan) and the Solomon Islands. Two species are found within Malesia and only one of these provides timber: G. spectabilis (Harms) Philipson (synonyms: G. boridiana Harms, Peekeliopanax spectabilis Harms) which occurs in New Guinea, the Bismarck Archipelago and the Solomon Islands.

Uses

The wood of G. spectabilis is used for light carpentry, boxes and fencing. It has also been used as core stock material for plywood.

Production and international trade

The wood of G. spectabilis is probably harvested on a local scale only.

Properties

G. spectabilis yields a lightweight hardwood with a density of 350-390 kg/m³at 11% moisture content. Heartwood white to creamy-white, not distinct from the sapwood; grain straight to occasionally wavy; texture moderately fine and even; wood highly lustrous. Growth ring boundaries absent; vessels medium-sized, just visible to the naked eye, solitary and in short radial multiples of 2-3 with clusters; parenchyma sparse, scanty paratracheal to vasicentric; rays medium-sized to moderately broad; ripple marks absent.

The wood is soft, splits easily and is liable to sap-stain.

See also the table on microscopic wood anatomy.

Botany

A medium-sized to large tree up to 40 m tall; bole branchless for up to 28 m, up to 175 cm in diameter, sometimes with buttresses up to 1 m high and 2 m wide; outer bark with small shallow fissures and prominent lenticels, brown; exudate abundant, clear and aromatic; crown sparsely branched. Leaves arranged spirally, crowded at the end of branches, imparipinnate, exstipulate, large, the rachis articulated; leaflets crenate. Inflorescence axillary, situated well below the leaves on a strong peduncle. Flowers small, in umbellules arranged racemosely on whorled inflorescence branches, cream; calyx forming a straight rim; petals valvate, fleshy; disk fleshy; ovary inferior, (10-)16(-22)-locular with a single ovule in each cell, styles subulate. Fruit a dark red or red-brown berry with the calyx rim, disk and stigmas persistent.

G. spectabilis may be the largest araliad known. It develops according to Leeuwenberg's architectural tree model in which 2 or more orthotropic modules develop below an inflorescence and these are equivalent and determinate by terminal flowering. Several flushes of vegetative growth occur as an inflorescence matures, so that by anthesis it is situated well below the leaves.

Ecology

G. spectabilis occurs in both primary and secondary rain forest at 200-2000 m altitude; also on cultivated and abandoned agricultural land.

Genetic resources and breeding

It is unlikely that the use of the timber of G. spectabilis is leading to a decrease in genetic diversity.

Prospects

The quality of the wood of Gastonia has never been fully studied and is little known, therefore it is very unlikely that its use will increase.

Literature

300, 341, 402, 403, 407, 423, 890, 1232.

E. Boer (general part),

M.S.M. Sosef (general part),

J. Ilic (wood anatomy)