1) Trees receive an estimated 90% of their nutrition from the atmosphere and only 10% from the soil.
2) Trees grow from the top, not from the bottom as is commonly believed. A branch's location on a tree will only move up the trunk a few inches in 1000 years.
3) No tree dies of old age. They are generally killed by insects, disease or by people. California Bristlecone Pines and Giant Sequoias are regarded as the oldest trees and have been known to live 4,000 to 5,000 years.
4) There are about 20,000 tree species in the world. The United States has one of the largest tree treasuries second only to India.
5) The largest area of forest in the tropics remains the Amazon Basin, amounting to 81.5 million acres.
6) Arbor Day was first observed in Nebraska in 1872. That state is now home to one of the world's largest forests planted by people - over 200,000 acres of trees.
7) Some trees can "talk" to each other. When willows are attacked by webworms and caterpillars, they emit a chemical that alerts nearby willow of the danger. The neighboring trees then respond by pumping more tannin into their leaves making it difficult for the insects to digest the leaves.
8) Knocking on wood for good luck originated from primitive tree worship when rapping on trees was believed to summon protective spirits in the trees.
9) Trees can induce rainfall by cooling the land and transpiring water into the sky from their leaves. An acre of maple trees can put as much as 20,000 gallons of water into the air each day.
10) The most massive living thing on earth is the Giant Sequoia in the Redwood Forest of California. It stands nearly 30 stories tall and 82.3 feet in circumference. Its weight is estimated at 2,756 tons.
