''Ochroma pyramidale'', commonly known as balsa, is a large, fast-growing

tree In botany, a tree is a perennial plant with an elongated stem, or trunk, usually supporting branches and leaves. In some usages, the definition of a tree may be narrower, e.g., including only woody plants with secondary growth, only ...

native to the Americas. It is the sole member of the

genus Genus (; : genera ) is a taxonomic rank above species and below family (taxonomy), family as used in the biological classification of extant taxon, living and fossil organisms as well as Virus classification#ICTV classification, viruses. In bino ...

''Ochroma'', and is classified in the subfamily

Bombacoideae Bombacoideae is a subfamily of the mallow family, Malvaceae. It contains herbaceous and woody plants. Their leaves are alternate, commonly palmately lobed, with small and caducous stipules. The flowers are hermaphroditic and actinomorphic; the c ...

of the mallow family

Malvaceae Malvaceae (), or the mallows, is a family of flowering plants estimated to contain 244 genera with 4225 known species. Well-known members of economic importance include Theobroma cacao, cacao, Cola (plant), cola, cotton, okra, Hibiscus sabdariffa, ...

. The tree is famous for its wide usage in

woodworking Woodworking is the skill of making items from wood, and includes cabinetry, furniture making, wood carving, joinery, carpentry, and woodturning. History Along with stone, clay and animal parts, wood was one of the first materials worked b ...

, due to its softness and its high strength compared to its low density. The name ''balsa'' is the Spanish word for "raft" and the Portuguese word for

ferry A ferry is a boat or ship that transports passengers, and occasionally vehicles and cargo, across a body of water. A small passenger ferry with multiple stops, like those in Venice, Italy, is sometimes referred to as a water taxi or water bus ...

. A deciduous

angiosperm Flowering plants are plants that bear flowers and fruits, and form the clade Angiospermae (). The term angiosperm is derived from the Greek words (; 'container, vessel') and (; 'seed'), meaning that the seeds are enclosed within a fruit ...

, ''Ochroma pyramidale'' can grow up to 30 m tall, and is classified as a

hardwood Hardwood is wood from Flowering plant, angiosperm trees. These are usually found in broad-leaved temperate and tropical forests. In temperate and boreal ecosystem, boreal latitudes they are mostly deciduous, but in tropics and subtropics mostl ...

despite the wood itself being very soft; it is the softest commercial hardwood and is widely used because of its light weight. Balsa trees grow extremely fast, often up to 27 metres in 10–15 years, and do not usually live beyond 30 to 40 years. In terms of volume (as opposed to height) they may be the fastest growing tree known; Streets mentions one individual which grew tall and

diameter at breast height Diameter at breast height, or DBH, is a standard method of expressing the diameter of the trunk or bole of a standing tree. DBH is one of the most common dendrometric measurements. Tree trunks are measured at the height of an adult's breast, ...

during a period of fifteen months. Balsa, like most

rainforest Rainforests are forests characterized by a closed and continuous tree Canopy (biology), canopy, moisture-dependent vegetation, the presence of epiphytes and lianas and the absence of wildfire. Rainforests can be generally classified as tropi ...

trees, does not make

annual rings Dendrochronology (or tree-ring dating) is the scientific method of dating tree rings (also called growth rings) to the exact year they were formed in a tree. As well as dating them, this can give data for dendroclimatology, the study of climate ...

, but this growth is equivalent to rings wide. They are often cultivated in dense patches, with

Ecuador Ecuador, officially the Republic of Ecuador, is a country in northwestern South America, bordered by Colombia on the north, Peru on the east and south, and the Pacific Ocean on the west. It also includes the Galápagos Province which contain ...

supplying 95% or more of the commercial balsa. The wood from these trees is highly valuable due to its high strength-to-weight ratio, which is achieved through a kiln-drying process that leaves the wood's cells hollow and empty. Balsa wood is popular for light, stiff structures in model bridge tests, model buildings, and construction of model aircraft. It is also used in the manufacturing of wooden crankbaits for fishing, makeshift pens for calligraphy, composites, surfboards, boats, "breakaway" props for theatre and television, and even in the floor pans of the

Chevrolet Corvette The Chevrolet Corvette is a line of American two-door, two-seater sports cars manufactured and marketed by General Motors under the Chevrolet marque since 1953. Throughout eight generations, indicated sequentially as C1 to C8, the Corvette is not ...

. Balsa wood played a historical role in Thor Heyerdahl's Kon-Tiki expedition where it was used to build the raft. Balsa wood is also popular in arts such as whittling, and in the making of baroque-style picture frames due to its ease of shaping.

Biology

Balsa on Bota Hill, Limbe Botanical Garden, Cameroon">Limbe_Botanical_Garden.html" ;"title="Bota Hill, Limbe Botanical Garden">Bota Hill, Limbe Botanical Garden, Cameroon A member of the mallow family, ''Ochroma pyramidale'' is native from southern Mexico to southern Brazil, but has been introduced to many other countries, including Papua New Guinea, Indonesia, Thailand, and the Solomon Islands. It is a pioneer plant, which establishes itself in clearings in forests, either man-made or where trees have fallen, or in abandoned agricultural fields. It grows extremely rapidly, up to in 10–15 years. The speed of growth accounts for the lightness of the wood, which has a lower density than cork. Trees generally do not live beyond 30 to 40 years. Flowers are produced from the third year onwards, typically at the end of the rainy season when few other trees are in flower. The large flowers, up to in diameter, open in the late afternoon and remain open overnight. Each may contain a pool of nectar up to deep. Daytime pollinators include

capuchin monkey The capuchin monkeys () are New World monkeys of the subfamily Cebinae. They are readily identified as the "Street organ, organ grinder" monkey, and have been used in many movies and television shows. The range of capuchin monkeys includes some t ...

s. However, most pollination occurs at night; the main pollinators were once thought to be bats, but recent evidence suggests that two nocturnal arboreal mammals, the kinkajou and the olingo, may be the primary pollinators. It is

evergreen In botany, an evergreen is a plant which has Leaf, foliage that remains green and functional throughout the year. This contrasts with deciduous plants, which lose their foliage completely during the winter or dry season. Consisting of many diffe ...

or dry-season

deciduous In the fields of horticulture and botany, the term deciduous () means "falling off at maturity" and "tending to fall off", in reference to trees and shrubs that seasonally shed Leaf, leaves, usually in the autumn; to the shedding of petals, aft ...

, with large , weakly palmately lobed leaves. Being a deciduous

, balsa is classified as a

despite the wood itself being very soft; it is the softest commercial hardwood.

Cultivation

Ecuador supplies 70% or more of commercial balsa. In recent years, about 60% of the balsa has been

plantation Plantations are farms specializing in cash crops, usually mainly planting a single crop, with perhaps ancillary areas for vegetables for eating and so on. Plantations, centered on a plantation house, grow crops including cotton, cannabis, tob ...

-grown in densely packed patches of around 1000 trees per hectare (compared to about two to three per hectare in nature). The trees are harvested after six to ten years of growth in Ecuador. The remaining volume of balsa is harvested from plantations in Papua New Guinea; the climate is different, therefore harvesting occurs at 4-5 years of age.

Uses

Balsa wood is very soft and light, with a coarse, open

grain A grain is a small, hard, dry fruit (caryopsis) – with or without an attached husk, hull layer – harvested for human or animal consumption. A grain crop is a grain-producing plant. The two main types of commercial grain crops are cereals and ...

. The

density Density (volumetric mass density or specific mass) is the ratio of a substance's mass to its volume. The symbol most often used for density is ''ρ'' (the lower case Greek letter rho), although the Latin letter ''D'' (or ''d'') can also be u ...

of dry balsa wood ranges from 40 to 475 kg/m³, with a typical density around 160 kg/m³. Balsa is the softest wood ever measured using the

Janka hardness test The Janka hardness test (; ), created by Austrian-born American researcher Gabriel Janka (1864–1932), measures the resistance of a sample of wood to denting and wear. It measures the force required to embed an steel ball halfway into a sample ...

(22 to 167 lbf). The wood of the living tree has large cells that are filled with water. This gives the wood a spongy texture. It also makes the wood of the living tree not much lighter than water and barely able to float. For commercial production, the wood is kiln-dried for about two weeks, leaving the cells hollow and empty. The large volume-to-surface ratio of the resulting thin-walled, empty cells gives the dried wood a large strength-to-weight ratio because the cells are mostly air. Unlike naturally rotted wood, which soon disintegrates in the

s where balsa trees grow, the cell walls of kiln- seasoned balsa wood retain their strong structure of

cellulose Cellulose is an organic compound with the chemical formula, formula , a polysaccharide consisting of a linear chain of several hundred to many thousands of glycosidic bond, β(1→4) linked glucose, D-glucose units. Cellulose is an important s ...

and

lignin Lignin is a class of complex organic polymers that form key structural materials in the support tissues of most plants. Lignins are particularly important in the formation of cell walls, especially in wood and bark, because they lend rigidit ...

. Because it is low in density but high in specific strength (strength per weight), balsa is a very popular material for light, stiff structures in model bridge tests, model buildings, and construction of

model aircraft A model aircraft is a physical model of an existing or imagined aircraft, and is built typically for display, research, or amusement. Model aircraft are divided into two basic groups: flying and non-flying. Non-flying models are also termed s ...

; all grades are usable for airworthy

control line Control line (also called U-Control) is a simple and light way of controlling a flying model aircraft. The aircraft is typically connected to the operator by a pair of lines, attached to a handle, that work the elevator of the model. This allo ...

and

radio-controlled aircraft A radio-controlled aircraft (often called RC aircraft or RC plane) is a small flying machine that is radio controlled by an operator on the ground using a hand-held radio transmitter. The transmitter continuously communicates with a receiver (rad ...

varieties of the aeromodeling sports, with the lightest "contest grades" especially valuable for free-flight model aircraft. However, it is also valued as a component of full-sized light wooden

aeroplane An airplane (American English), or aeroplane (Commonwealth English), informally plane, is a fixed-wing aircraft that is propelled forward by thrust from a jet engine, Propeller (aircraft), propeller, or rocket engine. Airplanes come in a vari ...

s, most notably the

World War II World War II or the Second World War (1 September 1939 – 2 September 1945) was a World war, global conflict between two coalitions: the Allies of World War II, Allies and the Axis powers. World War II by country, Nearly all of the wo ...

de Havilland Mosquito The de Havilland DH.98 Mosquito is a British twin-engined, multirole combat aircraft, introduced during the World War II, Second World War. Unusual in that its airframe was constructed mostly of wood, it was nicknamed the "Wooden Wonder", or " ...

. Balsa is used to make wooden crankbaits for fishing, especially

Rapala Rapala ( ) is a fishing product manufacturing company based in Finland. It was founded in 1936 by Lauri Rapala, who is credited for creating Original Floater, the world's first floating minnow lure carved from cork with a shoemaker's knife, c ...

lures. Sticks of dried balsa are useful as makeshift pens for

calligraphy Calligraphy () is a visual art related to writing. It is the design and execution of lettering with a pen, ink brush, or other writing instruments. Contemporary calligraphic practice can be defined as "the art of giving form to signs in an e ...

when commercial metal nibs of the desired width are not available. Balsa wood is often selected as a core material in composites. Because balsa grows quickly and tolerates poor soils, it is lower in cost per performance compared to polymer foams like

EPS An extended play (EP) is a Sound recording and reproduction, musical recording that contains more tracks than a Single (music), single but fewer than an album. Contemporary EPs generally contain up to eight tracks and have a playing time of 1 ...

while having better tensile strength than typical foams. For example, the blades of

wind turbine A wind turbine is a device that wind power, converts the kinetic energy of wind into electrical energy. , hundreds of thousands of list of most powerful wind turbines, large turbines, in installations known as wind farms, were generating over ...

s are commonly constructed of many balsa plywood cores and internal spars covered with resin infused cloth on both sides. In

table tennis Table tennis (also known as ping-pong) is a racket sport derived from tennis but distinguished by its playing surface being atop a stationary table, rather than the Tennis court, court on which players stand. Either individually or in teams of ...

rackets, a balsa layer is typically sandwiched between two pieces of thin

plywood Plywood is a composite material manufactured from thin layers, or "plies", of wood veneer that have been stacked and glued together. It is an engineered wood from the family of manufactured boards, which include plywood, medium-density fibreboa ...

made from other species of wood. Balsa wood is also used in

laminate Simulated flight (using image stack created by μCT scanning) through the length of a knitting needle that consists of laminated wooden layers: the layers can be differentiated by the change of direction of the wood's vessels Shattered windshi ...

s together with

glass-reinforced plastic Fiberglass (American English) or fibreglass ( Commonwealth English) is a common type of fiber-reinforced plastic using glass fiber. The fibers may be randomly arranged, flattened into a sheet called a chopped strand mat, or woven into glass c ...

(

fibreglass Fiberglass (American English) or fibreglass ( Commonwealth English) is a common type of fiber-reinforced plastic using glass fiber. The fibers may be randomly arranged, flattened into a sheet called a chopped strand mat, or woven into glass c ...

) for making high-quality balsa

surfboard A surfboard is a narrow plank used in surfing. Surfboards are relatively light, but are strong enough to support an individual standing on them while riding an ocean wave. They were invented in ancient Hawaii, where they were known as ''papa hee ...

s and for the decks and topsides of many types of

boat A boat is a watercraft of a large range of types and sizes, but generally smaller than a ship, which is distinguished by its larger size or capacity, its shape, or its ability to carry boats. Small boats are typically used on inland waterways s ...

s, especially pleasure craft less than 30 m in length. On a boat, the balsa core is usually end-grain balsa, which is much more resistant to compression than if the soft balsa wood were laid lengthwise. More than 90% of the world's Balsa wood volume is prepared into end grain panels for the composites industry, mostly used as structural cores in the wind turbine blades, where strength, rigidity, durable and environmentally sustainable materials are sought after. Balsa is also used in the manufacture of "breakaway" wooden props such as tables and chairs that are designed to be broken as part of theatre, movie, and television productions. The fifth and sixth generations of the

had

floor pan The floorpan is a large sheet metal Stamping (metalworking), stamping that often incorporates several smaller Welding, welded stampings to form the floor of a large vehicle and the position of its external and structural panels. In the case of ...

s composed of balsa sandwiched between sheets of

carbon-fibre reinforced plastic Carbon fiber-reinforced polymers (American English), carbon-fibre-reinforced polymers ( Commonwealth English), carbon-fiber-reinforced plastics, carbon-fiber reinforced-thermoplastic (CFRP, CRP, CFRTP), also known as carbon fiber, carbon comp ...

. The Norwegian scientist and adventurer

Thor Heyerdahl Thor Heyerdahl KStJ (; 6 October 1914 – 18 April 2002) was a Norwegian adventurer and Ethnography, ethnographer with a background in biology with specialization in zoology, botany and geography. Heyerdahl is notable for his Kon-Tiki expediti ...

, convinced that early contact between the peoples of

South America South America is a continent entirely in the Western Hemisphere and mostly in the Southern Hemisphere, with a considerably smaller portion in the Northern Hemisphere. It can also be described as the southern Subregion#Americas, subregion o ...

and

Polynesia Polynesia ( , ) is a subregion of Oceania, made up of more than 1,000 islands scattered over the central and southern Pacific Ocean. The indigenous people who inhabit the islands of Polynesia are called Polynesians. They have many things in ...

was possible, built the raft '' Kon Tiki'' from balsa logs, and on it his crew and he sailed the

Pacific Ocean The Pacific Ocean is the largest and deepest of Earth's five Borders of the oceans, oceanic divisions. It extends from the Arctic Ocean in the north to the Southern Ocean, or, depending on the definition, to Antarctica in the south, and is ...

from

Peru Peru, officially the Republic of Peru, is a country in western South America. It is bordered in the north by Ecuador and Colombia, in the east by Brazil, in the southeast by Bolivia, in the south by Chile, and in the south and west by the Pac ...

to the Polynesian

Tuamotu Archipelago The Tuamotu Archipelago or the Tuamotu Islands (, officially ) are a French Polynesian chain of just under 80 islands and atolls in the southern Pacific Ocean. They constitute the largest chain of atolls in the world, extending (from northwest to ...

in 1947. However, the ''Kon Tiki'' logs were not seasoned and owed much of their (rather slight) buoyancy to the fact that their sap was of lower density than sea water. This serendipitously may have saved the expedition, because it prevented the seawater from waterlogging the wood and sinking the raft. Balsa wood is also a popular wood type used in the arts of

whittling Whittling may refer either to the art of carving shapes out of raw wood using a knife or a time-occupying process of repeatedly shaving slivers from a piece of wood. It is used by many as a pastime, or as a way to make artistic creations. Backgr ...

, and

surfing Surfing is a surface water sport in which an individual, a surfer (or two in tandem surfing), uses a board to ride on the forward section, or face, of a moving wave of water, which usually carries the surfer towards the shore. Waves suita ...

. In the making of picture frames, balsa was often used in a baroque style because of the ease of shaping the design. In parts of Africa and south America the leaves of the balsa tree are used to enhance the traditional

panning Pan or PAN may refer to: Food * Pan (cooking), a piece of cooking equipment * Harina P.A.N., a pre-cooked corn meal * Pan or Paan, a North Indian term for betel Prefix * ''Pan-'', a prefix meaning "all", "of everything", or "involving all ...

method of extracting gold from ore. When mixed with water a soapy solution is produced and this helps the lighter, unwanted material to wash away.

Gallery

file:Ochroma pyramidale1FrancesWHorne.jpg, Painting by Frances W. Horne from the Flora Borinqueña file:Ochroma pyramidale Maui.jpg, ''Ochroma pyramidale'' at Tropical Gardens of Maui Iao Valley Rd,

Maui Maui (; Hawaiian language, Hawaiian: ) is the second largest island in the Hawaiian archipelago, at 727.2 square miles (1,883 km2). It is the List of islands of the United States by area, 17th-largest in the United States. Maui is one of ...

file:Balsas_and_kayak.jpg, Two balsa rafts and a kayak at Lagos de Montebello in Chiapas, Mexico file:Balsa airframe.jpg, Balsa construction in a "stick and tissue" free-flight rubber scale model airplane

References

External links