Adinauclea (PROSEA)

Plant Resources of South-East Asia Introduction

List of species

Adinauclea Ridsd.

Protologue: Blumea 24: 349 (1978).

Family: Rubiaceae

Chromosome number: x= unknown; 2n= unknown

• Indonesia: kayu lasi (Moluccas), kilali (Buru, Moluccas).

Adinauclea is a monotypic genus confined to Sulawesi and the Moluccas. The only species is A. fagifolia (Teijsm. & Binnend. ex Havil.) Ridsd. (synonyms: Adina fagifolia (Teijsm. & Binnend. ex Havil.) Valeton ex Merr., Nauclea fagifolia Teijsm. & Binnend. ex Havil., Neonauclea fagifolia (Teijsm. & Binnend. ex Havil.) Merr.).

The wood of A. fagifolia has been in demand for the manufacture of furniture and has also been used for building traditional boats.

Small amounts of this timber were traded in the 1920s from northern Sulawesi, but nowadays A. fagifolia trees are too scarce to be important.

A. fagifolia yields a medium-weight hardwood with a density of 770-880 kg/m³at 15% moisture content. Heartwood pale yellow to pink-yellow, with whitish flecks or streaks, turning pale with age, slightly differentiated from the somewhat paler sapwood; grain straight, sometimes slightly interlocked; texture very fine and even; with an aromatic odour when freshly cut. Growth rings not distinct; vessels very small, mostly solitary and few radial multiples; rays very fine; ripple marks absent.

The wood dries slowly and needs care in seasoning to prevent surface checks. It is hard and moderately strong. It works easily, probably easiest when seasoned, and a good polish can be obtained, but it splits easily. The wood is moderately durable and probably resistant to termites and dry rot.

See also the table on microscopic wood anatomy.

A large tree up to 45 m tall; bole branchless for up to 30 m, up to 200(-240) cm in diameter. Terminal vegetative bud flattened. Leaves opposite, simple, entire, with appressed and caducous stipules. Flowers in 1 or 3 heads terminal at branches, 5-merous, interfloral bracteoles present; calyx with a short tube and elliptical-oblong lobes; corolla infundibular, with valvate lobes (but subimbricate at apex); stamens inserted in the upper part of the corolla tube; ovary inferior, 2-locular; style exserted, with globose stigma. Fruit in a head-like infructescence, free, splitting in 4 parts, with persistent central axis. Seed ovoid, bilaterally compressed. Seedling with epigeal germination; cotyledons leafy.

The tree develops according to Troll's architectural tree model, characterized by a sympodial trunk with all axes plagiotropic with continual superposition.

Adinauclea is related to Adina and a group of 4 small "satellite" genera (including Haldina , Metadina and Pertusadina ) in the tribe Naucleeae . It differs particularly in the strongly flattened terminal vegetative bud and in the mode of dehiscence of the fruit: the calyx remnant detaches with the segments of the fruit wall, whereas in Adina and the other related genera the calyx remnant remains attached to the central axis of the fruit.

A. fagifolia occurs in forest from sea-level to mountainous areas, often in stony locations, and both on wet and dry soils.

Silviculture It has been reported from Sulawesi that collecting seed is extremely difficult. In natural forest on the island of Boano (the Moluccas) some 30 trees/ha were found with a timber volume of 40 m³, whereas in North Sulawesi an estimated average exploitable timber volume of 50 m³/ha has been reported for a forest type covering about 8000 ha. Hardly any natural regeneration was observed in this latter forest during the inventory. Therefore, exploitation should be followed by artificial regeneration, e.g. enrichment planting. A single log can supply 40-60 m³of timber.

The supply of this timber had already declined considerably in the 1920s because of the great demand. It is not known whether the remaining A. fagifolia populations are in danger of extinction, but the species very probably needs protection.

A. fagifolia is a promising timber because of its large size and favourable wood properties for furniture manufacture. Therefore, research on the silvicultural aspects is needed to determine the feasability of sustainably managing the remaining natural stands and of planting new stands.

402, 436, 861, 943, 1130, 1165.

E. Boer & R.H.M.J. Lemmens