Metadina (PROSEA)

Plant Resources of South-East Asia Introduction

List of species

Metadina Bakh. f.

Protologue: Taxon 19: 472 (1970).

Family: Rubiaceae

Chromosome number: x= unknown; 2n= unknown

Vernacular names

• Indonesia: kayu kunyit, ki anggrit (Java), nangi kuning (Sumatra)
• Malaysia: berombong, meraga (Peninsular), mengkeniab (Sabah)
• Philippines: Zschokke adina (general)
• Thailand: khamin (northern), khem chang, lang khao (peninsular)
• Vietnam: vàng vé.

Origin and geographic distribution

Metadina is a monotypic genus. The species M. trichotoma (Zoll. & Moritzi) Bakh. f. (synonyms: Adina polycephala Benth., Adina zschokkei Elmer, Nauclea trichotoma Zoll. & Moritzi) occurs in India, Burma (Myanmar), Cambodia, Vietnam, Thailand, Peninsular Malaysia, Sumatra, Java, Borneo and the Philippines.

Uses

The wood of M. trichotoma is used for house building (e.g. for planks), flooring, fence posts, joinery, turnery, tool handles and agricultural implements.

The bark is used as a tonic in local medicine in Indonesia and Thailand.

Production and international trade

The timber of M. trichotoma is used only locally and supplies are too limited to be of importance.

Properties

M. trichotoma yields a heavy hardwood with a density of 860-940 kg/m³air dry. Heartwood yellow, yellow-brown or orange-red, sharply or not sharply demarcated from the paler, 3-6 cm wide sapwood; grain straight, occasionally interlocked; texture fine and even. Growth rings indistinct, sometimes suggested by a narrow layer without parenchyma succeeded by a layer with more numerous vessels; vessels moderately small to medium-sized, almost exclusively solitary, but with occasional radial multiples of 2-3, open; parenchyma abundant, apotracheal diffuse and diffuse-in-aggregates, hardly visible with a hand lens; rays extremely fine to moderately fine; ripple marks absent.

The wood is hard and easy to work. It is very durable and remains serviceable as freshwater piles for 5-15 years, for 8-10 years as poles in the ground, for 15 years for boats and for 60-100 years for construction under cover.

See also the table on microscopic wood anatomy.

Botany

A medium-sized to fairly large tree up to 40 m tall; bole straight, sometimes slightly fluted, up to 50 cm in diameter; bark surface smooth to finely fissured and flaky, greyish-brown, inner bark pink to red. Terminal vegetative bud pyramidal to conical. Leaves opposite, simple, entire, elliptical to obovate, acuminate; stipules overlapping, caducous. Flowers in numerous stalked heads borne terminally on 1-3 flowering axes which are each branched like a compound thyrse, 5-merous; interfloral bracteoles present; calyx with a short tube and persistent elliptical-oblong lobes; corolla hypocrateriform to narrowly funnel-shaped, with valvate lobes (but subimbricate at apex); stamens inserted in the upper part of the corolla tube; ovary inferior, 2-locular with 4-12 ovules in each cell, style exserted, stigma globose to clavate, smooth. Fruits in a head-like infructescence, free, splitting into 4 parts, with persistent central axis and calyx. Seed trigonal, slightly bilaterally compressed, not winged. Seedling with epigeal germination; cotyledons leafy; hypocotyl elongated.

Metadina is related to Adina and a group of 4 small "satellite" genera (including Adinauclea , Haldina and Pertusadina ) in the tribe Naucleeae . It is recognizable particularly by the pyramidal or conical terminal vegetative bud and the numerous flowering heads on a branched axis.

Ecology

M. trichotoma occurs in primary forest, particularly in hilly and mountainous locations, up to 1300 m altitude. In most regions it is uncommon, and locally even rare (e.g. in Java).

Genetic resources and breeding

M. trichotoma has a large area of distribution and does not seem to be endangered. However, it needs protection in regions where it is rare, such as Java.

Prospects

The wood of M. trichotoma is used only locally and increased use for sawn timber is not very likely, as timber of large dimensions is rare. As the wood is hard and durable, however, research on its silviculture and propagation seems justified.

Literature

162, 163, 267, 436, 861, 943, 1165, 1221, 1242.

Isa Ipor