Ochroma bicolor Rowlee

Deciduous or evergreen, medium-sized or rarely large trees up to 30(-50) m tall; bole straight, usually short, cylindrical, up to 100(-180) cm in diameter, with short buttresses in older trees; bark surface smooth, grey-white mottled. Leaves arranged spirally, simple, angular-lobate, palmately veined; stipules present. Flowers axillary, solitary; calyx tubular, with 5 unequal lobes; petals 5, whitish; stamens united into a briefly 5-lobed staminal column bearing sessile wavy anthers from the middle to the apex; ovary superior, 5-locular with many ovules in each cell, style club-shaped, stigma spiralled. Fruit an oblong, ribbed, 5-valved dehiscent capsule, densely lanate inside. O. pyramidale is highly variable, which is probably why the genus was formerly thought to comprise at least 11 species. Growth of O. pyramidale trees can be extremely rapid and is according to Koriba's architectural tree model, characterized by orthotropic axes which branch to produce initially equivalent modules. Subsequently one of these modules becomes dominant, constituting one unit of the sympodial trunk.

In Java and Peninsular Malaysia O. pyramidale flowers throughout the year and is pollinated by bats. Trees start producing viable seed after (2-)3-4 years and dispersal is by wind.

It grows gregariously with a preference for alluvial flats, on rich, well-drained or volcanic soils.

O. pyramidale is a typical pioneer, colonizing clearings. It can tolerate a dry season of up to 4 months, but only if the relative humidity does not normally drop below 75%.

Ochroma is a monotypic genus occurring in tropical Central and South America from southern Mexico to Bolivia. The only species is O. pyramidale (Cav. ex Lamk) Urban which is planted in many tropical countries; in the Malesian region in the Philippines, Malaysia, Java and Papua New Guinea where it has locally become naturalized.

O. pyramidale can be propagated by seed. The very fine seeds (112 000-150 000 dry seeds/kg) should be collected from standing trees. In Papua New Guinea seed is collected in June-August. Seeds can be sown directly in the field or in the nursery. Freshly collected seed has only 10% germination. Seeds contain an impervious testa which must be ruptured by heat (boiling water, fire) before they will germinate. Under natural conditions forest clearance exposes the soil to the sun and this triggers germination of Ochroma seeds. In the nursery seeds are sown in lines 3-4 cm apart under slight shade and in sterilized soil to prevent damping-off. Pretreated seeds show 65-75% germination in 6-28 days and seedlings are pricked out and transferred to containers.

Plantation: When seedlings are 3-4 months old and 20-25 cm tall, they can be planted out in the field at 4-5 m x 4-5 m, possibly in a taungya system with a spacing of 2 m x 3 m. In Papua New Guinea a higher initial density of 2268 trees/ha (about 2.1 m x 2.1 m) is applied. As the roots of young plants are extremely sensitive to damage, bare-rooted plants cannot be used and direct seeding is preferred using seed holes at 3 m x 3 m. The soil should be deep, well-aerated and fertile, to allow for rapid growth; slightly inferior sites retard growth and will produce wood with a higher density (over 160 kg/m¦), which is not of commercial interest as only the extremely lightweight wood is in demand. Husbandry: Thinning is comparatively heavy and aims at creating enough growing space for the trees to allow for rapid growth. For Papua New Guinea a reduction of the initial 2268 trees/ha to 99 trees/ha before clear felling at the age of five is advocated. A rotation of 8 years is applied in Indonesia with a reduction in stems from 900-1225 to 90-170 per ha, depending on the site. Great care should be taken to avoid damage to the remaining trees, as they heal very poorly or not at all. A mean annual volume increment of 17-30 m¦/ha can generally be expected, although 69 m¦/ha and 90 m¦/ha has been achieved in Indonesia in 8- and 6-year-old plantations, respectively and 50 m¦/ha is commonly accepted as realistic. Rotations do not generally exceed 7-8 years, as the rapid growth slows down appreciably after 7-12 years. At this age heartwood development starts with a much higher density and a darker colour rendering it less suitable for the special purposes. After harvest, residues can be burnt, which gives rise to abundant natural regeneration.

Pests: Zeuzera coffeae, a wood borer, has been observed in a 1.5-year-old plantation in Java seriously damaging the majority of trees which had to be clear felled to avoid attack of other trees.

The very fine seeds (112 000-150 000 dry seeds/kg) can be stored for several years in jute bags or in closed receptacles.

Ornamental: The tree is sometimes planted as an ornamental. Shade or shelter: The tree is sometimes planted as provide shade expediently.

Fibre: For the production of pulp and paper. Ropes have been made from the fibrous bark. Timber: The extremely lightweight wood of Ochroma is used for buoys, life-jackets and life-belts, surf boards, aircraft construction, toys, model making, entomology mounting boards, core stock in sandwich construction, surgical splints, packaging of fragile articles and as insulation for heat, vibration, sound and formerly also for electricity. The heavier wood of Ochroma is suitable for matches, popsicle sticks, toothpicks, etc. Other products: The kapok from the fruits is suitable for filling pillows and mattresses.