Brownlowia (PROSEA)

Plant Resources of South-East Asia Introduction

List of species

Brownlowia Roxb.

Protologue: Pl. Coromandel 3: 61 (1820).

Family: Tiliaceae

Chromosome number: x= unknown; 2n= unknown

Origin and geographic distribution

Brownlowia comprises about 28 species occurring from India and Bangladesh to Burma (Myanmar), Indo-China, Thailand and the Malesian region except for Java and the Lesser Sunda Islands, east to the Solomon Islands and south to northern Australia. Borneo is regarded as the centre of diversity with 19 species.

Uses

In Papua New Guinea the wood of Brownlowia is used for pallets and is considered suitable for mouldings and interior finish.

Production and international trade

The wood of Brownlowia is used on a local scale only.

Properties

Brownlowia yields a lightweight to medium-weight hardwood with a density of 465-640 kg/m³at 15% moisture content. Heartwood red-brown to brown, sapwood yellow-brown to pale yellow. Growth rings distinct; vessels moderately small, solitary and in radial multiples of 2-4; parenchyma apotracheal diffuse and diffuse-in-aggregates, paratracheal vasicentric, narrow; rays fine to moderately fine; ripple marks present.

Air drying of the wood of B. stipulata Kosterm. is fairly slow and it takes 3 months for 13 mm thick boards and 5 months for 38 mm thick boards to air dry from green to 20% moisture content. The wood is only moderately strong and non-durable. It is probably susceptible to Lyctus .

See also the table on microscopic wood anatomy.

Botany

Evergreen shrubs or small to medium-sized trees up to 30 m (outside Malesia up to 40 m) tall; bole often crooked, sometimes branchless for up to 13 m, up to 50 cm (outside Malesia up to 150 cm) in diameter, usually with small concave buttresses; bark surface smooth becoming papery flaked, hoop-marked, pale ochrous to grey-brown, inner bark dark reddish-brown. Indumentum of stellate hairs and/or scales. Leaves arranged spirally, simple, sometimes peltate, entire, usually broadly ovate, palmately or pinnately veined, often fimbriate scaly below, stipulate; petiole thickened at both ends. Flowers in a terminal panicle; calyx bell-shaped with 5 teeth; petals 5; stamens many, free or connate at base, often in 5 bundles, staminodes 5; ovary with 5 loosely connected, ribbed carpels each with 2 ovules, style long, simple. Fruit with 1-5, free, 1-seeded, woody carpels splitting open along a groove or ridge at the back. Seed without endosperm. Seedling with epigeal germination; cotyledons emergent, leafy; hypocotyl elongated; seedling leaves toothed, all alternate-spiral.

In Thailand B. peltata flowers and fruits from February to August. The fruits float in water and are thus dispersed.

In India and Indo-China B. elata Roxb. and B. tabularis Pierre represent large trees whose wood is reported to be very durable and to be used for luxury furniture.

It may well be that B. helferiana Pierre is conspecific with B. peltata , which would extend the range of the latter to Burma (Myanmar), peninsular Thailand and Peninsular Malaysia.

Ecology

Brownlowia species are locally frequent in primary evergreen forest, up to 600 m altitude. They prefer swamps or damp or periodically inundated locations, sometimes on hills or along rivers, in mixed dipterocarp forest, usually on clayey soils, but B. peltata prefers well-drained soils. B. argentata constitutes a common element of the vegetation along tidal rivers towards the inner mangroves, especially on sandy soils.

Silviculture Brownlowia may be raised from seed. About 40% of the sown fruits of B. helferiana germinated in 4-31 days.

Genetic resources and breeding

There are no records of in situ or ex situ conservation. The indiscriminate clearing of mangrove forest for economic activities may significantly endanger Brownlowia species like B. argentata . Its comparatively wide distribution and efficient seed dispersal, however, diminish the risk of genetic erosion.

Prospects

As information on Brownlowia timber is scanty, economic interest is still extremely low and this is not expected to change in the near future.

Literature

61, 163, 209, 348, 400, 464, 609, 612, 829, 831, 887, 974, 1039, 1221.