Brackenridgea (PROSEA)

Plant Resources of South-East Asia Introduction

List of species

Brackenridgea A. Gray

Protologue: Char. new gen. pl.: 5 (1853).

Family: Ochnaceae

Chromosome number: x= unknown; 2n= unknown

Vernacular names

• Brown ochna (En, trade name).

Origin and geographic distribution

Brackenridgea comprises about 8 species occurring in tropical East Africa and Madagascar, and in the Andaman Islands, Thailand, Peninsular Malaysia, Sumatra, Borneo, the Philippines, Sulawesi, New Guinea, Australia (Queensland) and Fiji. Within the Malesian region 4 species are present.

Uses

The wood of Brackenridgea is used for rafters in house building.

The leaves of B. hookeri used to be chewed as a masticatory in Peninsular Malaysia.

Production and international trade

The wood of Brackenridgea is used rarely and on a local scale only.

Properties

Brackenridgea yields a medium-weight hardwood with a density of 710-790 kg/m³at 15% moisture content. Heartwood red-brown, sapwood white to pale yellow; texture fine. Growth rings indistinct; vessels small to medium-sized, exclusively solitary; parenchyma not abundant, apotracheal diffuse, and scanty paratracheal to unilaterally paratracheal sometimes appearing aliform; rays fine to moderately fine; ripple marks absent.

The wood is fairly strong and hard, moderately durable under cover and resistant to insect attack. The sapwood is considered to be non-susceptible to Lyctus .

See also the table on microscopic wood anatomy.

Botany

Small to medium-sized trees up to 35 m tall; bole straight, cylindrical, up to 60(-120) cm in diameter, sometimes slightly fluted or with small buttresses; bark surface smooth to slightly fissured and scaly, brown to reddish-brown or greyish-brown, inner bark pinkish-brown or reddish-brown. Leaves alternate, simple, entire or finely toothed, lateral veins strongly curved to the apex and often some of the lower ones parallel to the margin; stipules divided into several pointed lobes, caducous. Inflorescence thyrsoid, composed of simple or compound condensed cymes. Flowers regular; sepals 5, enlarged, fleshy and red in fruit; petals 5-10, white or yellow; stamens 10-many, in 1-several whorls; gynophore hemispherical; carpels 5-10, each with a single ovule, free but sharing a common style. Fruiting head with 1-2(-5) drupelets, greenish or reddish, becoming almost black when ripe.

Branches are spreading and monopodial. Flowering and vegetative growth tend to occur alternately. Seed dispersal is mainly by birds attracted by the black fruits contrasting with the red calyx and gynophore. The fruits also float due to 2 air-filled spaces between the inner and outer fruit wall.

Brackenridgea has been divided into 2 sections: in sect. Brackenridgea all flowers in a cyme open simultaneously, the white corolla is 5-merous, stamens 10 and carpels 5; in sect. Notochnella (v. Tiegh.) Kanis the flowers in a cyme open successively, the corolla is yellow and irregular, stamens many, in more than 1 whorl and carpels 5-10. Within B. palustris 3 subspecies are recognized: subsp. foxworthyi (Elmer) Kanis confined to Palawan, subsp. kjellbergii Kanis to Sulawesi, and subsp. palustris occuring in Peninsular Malaysia, Sumatra and Borneo.

Ecology

Brackenridgea is found scattered in evergreen, primary lowland and hill forest, up to 750(-1000) m altitude. It is confined to the perhumid regions. Vegetation types include kerangas and peat-swamp forest. It occurs on a wide range of usually rather poor soils, from clay to sand or peat. B. forbesii has been reported from ultrabasic soils.

Genetic resources and breeding

As Brackenridgea is not commercially exploited there is no risk of genetic erosion.

Prospects

It is unlikely that the use of Brackenridgea for timber will increase in the near future.

Literature

163, 198, 304, 341, 403, 436, 523, 861, 1038, 1039, 1048, 1221.