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Ochroma pyramidale, commonly known as Balsa, is a species of flowering plant in the mallow family, Malvaceae. It is a large, fast-growing tree that can grow up to tall. Balsa trees are native from southern Brazil and Bolivia north to southern Mexico however Ecuador has been the primary source of commercial Balsa. In recent years some Balsa has been plantation grown. It is evergreen, or dry-season deciduous if the dry season is long, with large weakly palmately lobed leaves. The name balsa derives from Spanish for a raft. Despite being very soft, balsa is classified as a hardwood, and is the softest commercial hardwood.
Balsa lumber is very soft and light with a coarse, open grain. The density of dry balsa wood ranges from 40340 kg/m (2.5-21 lb/ft), with a typical density of about 160 kg/m (10 lb/ft). It is also a very popular material to use when making wooden crankbaits for fishing, as it is low density but high in strength. Balsa wood is used to make very light, stiff structures in model bridge tests and for the construction of light wooden aeroplanes, most famously the World War II de Havilland Mosquito. It is also used in the floor pan of the Chevrolet Corvette Z06 sandwiched between two sheets of carbon fiber-reinforced polymer. In table tennis paddles, a balsa layer is typically sandwiched between two pieces of thin plywood. Balsa wood is also used in laminates with glass-reinforced plastic (fiberglass) for making high-quality balsa surfboards and the decks and topsides of many types of boats, especially pleasure craft under in length.
Balsa wood is often used as a core material in composites, for example, many wind turbines are made partially of balsa. It also remains a popular material for model aircraft, offering an excellent balance of strength and low density.
The light weight of the wood derives from the fact that the tree has large cells that contain water. After the water is driven off in an extended drying process, the resulting hole has a large surface to give strength. Unlike dry rotted wood, the surface is made of the usual strong cellulose/lignan mix.
Norwegian scientist/adventurer Thor Heyerdahl, convinced that early contact between the peoples of South America and Polynesia was possible, built from Balsa wood, the raft Kon Tiki upon which he and his crew sailed the Pacific Ocean from Peru to the Polynesian Tuamotu Archipelago in 1947.
Photo of foliage and flower
Kon-Tiki museum website
This article is licensed under the GNU Free Documentation License. It uses material from the Wikipedia article Ochroma pyramidale