A highly variable species, it has in the past been separated into 11 different species[].

Common Name: Balsa Wood

General Information

Balsa wood is a large, very fast-growing, evergreen tree with a large, wide, flat crown[, , ]. It can reach a height of 30 metres, with occasional specimens up to 50 metres[, ]. The bole is straight, usually short, cylindrical, up to 100 - 180cm in diameter, with short buttresses in older trees[].
Balsa wood timber is the lightest known commercial timber, it has a very wide range of applications but is probably best known as a material for making model planes etc. It has been widely planted in many tropical areas, though 90% of all commercial supplies are grown in Ecuador[, ]. The tree is an excellent pioneer species for restoring native woodland and establishing woodland gardens; it is sometimes planted as an ornamental or to provide shade[].

Known Hazards

None known

Botanical References

, ,

Range

S. America - Bolivia, north to the Caribbean and through Central America to Guatemala.

Habitat

Moist, lowland, limestone forest[]. Common along the margins of lakes or in disturbed areas, rare in the older forest where it is a large tree[]. It is found mainly on fertile, bottom-land soils along the sides of streams[].

Properties

Medicinal Rating
Other Uses Rating
Habit	Evergreen Tree
Height	30.00 m
Growth Rate	Fast
Pollinators	Bats, Birds
Cultivation Status	Cultivated, Ornamental, Wild

Cultivation Details

A plant of the lowland humid tropics, also succeeding at elevations up to 1,000 metres[]. It grows best in areas where annual daytime temperatures are within the range 18 - 35°c, but can tolerate 15 - 38°c[]. When dormant, the plant can survive temperatures down to about 5°c[]. It prefers a mean annual rainfall in the range 2,500 - 3,000mm, but tolerates 1,500 - 4,000mm[]. It can tolerate a dry season of up to 4 months, but only if the relative humidity does not normally drop below 75%[].
Prefers a deep, fertile, moisture-retentive but well-drained soil in a sunny position[, ]. Prefers a pH in the range 5.5 - 6.5, tolerating 5 - 8[]. Plants are very tolerant of salt-laden winds[].
A very fast-growing, but short-lived tree[]. It can reach a height of 20 metres, with a bole diameter of up to 60cm within 7 years and has been known to grow even faster on very rich soils[].
Trees can commence flowering and producing viable seeds when 3 - 4 years old[]. They can flower and produce seed all year round[].
Trees usually reach maturity when about 12 - 15 years old, after which they deteriorate rapidly, growth slows, the heartwood becomes waterlogged and doty (not sure what this means; it might be based on dotage - becoming old and senile[]), and the new growth is hard and heavy[].
Annual wood production potential is 17 - 30 cubic metres per hectare[].
The tree is highly sensitive to fire damage[].

Edible Uses

None known

Medicinal

The root bark is emetic[].

Agroforestry Uses:

A typical pioneer species, fast-growing and rapidly colonizing clearings[, ].

Other Uses

The woolly fibre contained in the seedpods has sometimes been used like kapok as a stuffing material in pillows and mattresses[, , , , ].

The fibre obtained from the bark has been used to make ropes[, ].

The heartwood is white to grey-white, sometimes with a pinkish tinge near the heart in older trees; it is not demarcated from the sapwood. The grain is straight; texture coarse and even; the lustre silky. The heartwood is too heavy to be of economic importance and most of the commercially used stock is sapwood. The wood is extremely light in weight - it is the lightest known commercial timber, being even lighter than cork. High-grade timber weighs less than 150 kg/m³ at 12% moisture content and is generally produced by young trees 8 - 9 years old, whereas older trees produce heartwood, which is heavier and is considered of secondary quality. Large differences exist between the outermost sapwood and that from nearer the centre - the new wood in the outer 3cm being on average 2.2 times heavier than the old wood in the inner 3cm. The wood is very soft and weak, but with a good strength to weight ratio, and that from old trees tends to be brittle. It is non-durable and prone to attack by Anobium and Lyctus borers, termites and longhorn beetles. The rates of shrinkage from green to oven dry are small to medium, kiln drying is preferable to air drying, to minimize splitting and warping. Movement in service is small. The wood is very easy to work with hand and machine tools, but sharp tools are needed to prevent crumbling. It takes nails and screws readily, but is too soft to hold them well. Planing is almost impossible; gluing properties are good, and the wood stains, polishes and paints satisfactorily, but it is very absorbent. Bending properties are poor. Balsa possesses an unusually high degree of buoyancy and is a very efficient insulation against heat and sound, it can be used at very low temperatures (down to -250°c). Some older trees develop a pink heartwood that tends to be brittle and is much inferior to the sapwood.
The wood is suitable for pulping by chemical and semi-chemical processes, yielding 45 - 50% pulp with good strength characteristics. The pulp can be easily bleached without loss of strength, making it suitable for printing and writing papers. The extremely lightweight wood is used for floats, buoys, lifejackets and life-belts, surf boards, aircraft construction, ship and boat building, lightweight boxes, toys, model making, laboratory mounting boards, core stock in sandwich construction, surgical splints, packaging of fragile articles and as insulation for temperature, vibration, sound and formerly also for electricity. Slightly heavier wood is suitable for matches, popsicle sticks and toothpicks, and for the production of pulp and paper[, , , , ].

Propagation

Seed - needs high temperatures to germinate[]. 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 - 4cm apart under slight shade and in sterilized soil to prevent damping-off. Pre-treated seeds show 65 - 75% germination in 6 - 28 days and seedlings are pricked out and transferred to containers[].
The very small seeds should be collected from standing trees, and can be stored for several years in jute bags or in closed containers[].

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