Allan McKee, age 13, of Watertown, N.Y., for his question:

DO BALSA TREES GROW FAST?

One of the fastest growing trees is the balsa. During the first six months of the tree's life, it may grow as much as 12 feet. During the tree's first 10 years, it may grow to a height of 90 feet and have a 15 inch diameter.

Ecuador grows most the world's commercial supply of balsa.

Spanish explorers first discovered natives using balsa wood for rafts. Balsa, as a matter of fact, is the Spanish word for raft or float.

Large ivory colored flowers and heart shaped leaves are features of the balsa tree. The tree also produces many seeds that are carried by the wind on silky threads. The seeds sprout quickly.

Balsa is the lightest wood known. It is only halt as heavy as cork.

Balsa is strong, yet soft and easy to work with. It is used for life preservers, floats and model boats and airplanes. In addition, it goes into soundproofing, insulation and even artificial limbs.