Missour1 Botanical 
Garden Bulletin 
Vol. III St. Louis, Mo., August, 1915 No. 8 
THE LIGHTEST KNOWN WOOD 
During the past month some samples of a very interesting 
wood, known commercially as Balsa wood, have been in- 
stalled in the Museum at the Missouri Botanical Garden. 
Balsa wood is cut from a tree known scientifically as Ochroma 
Lagopus, belonging to the order Bombaceae. It is closely 
related to the silk cotton tree, or Ceiba (Eriodendron anfrac- 
tuosum). Ochroma Lagopus grows throughout the West 
Indies and Central America. In reporting on the forest trees 
of Porto Rico, Professor John C. Gifford states that it is one 
of the commonest trees in Porto Rico. In a recent letter re- 
ceived from Prof. Gifford, he states, “Ochroma Lagopus is 
scattered all over the West Indies wherever I have been, but 
‘scattered,’ seldom in bunches of any consequence. ‘Trees 
grow to be a foot or more in diameter. I have never seen 
any big ones.” The wood is known by various common 
names. In Porto Rico it is goano or corkwood; in Martin- 
ique it is known as floating wood; in Cuba as lanero. 
Balsa wood is of very great interest because of its extreme 
light weight. In fact, so far as known, with the possible ex- 
ception of one of the species of pond apple (Anona), it is 
the lightest known wood. In the accompanying photograph 
a piece of Balsa wood is shown on one side of a pair of scales 
in comparison with a piece of ironbark (Hucalyptus leucoxy- 
lon) from Australia. The two pieces of wood are of exactly 
the same width and thickness, but the piece of Balsa wood is 
about ten times the length of the ironbark, and yet both sides 
of the scales balance. Balsa wood has a specific gravity of .11, 
weighing about 7.3 pounds per cubic foot. Ironbark has 
a specific gravity of 1.13, or a weight of 70.5 pounds per 
cubic foot; that is, it is about ten times as heavy as Balsa 
wood. The extremely light character of the wood is well 
shown in the accompanying comparative table showing the 
weight in pounds per cubic foot of various American woods: 
(107) 
