How Trees Know Their Birthdays.
Willard wondered how old the pretty graceful maple that grew outside his window was.
"I don't know exactly," said mother, "five or six years I should think. But the maple has the story of each birthday shut up safe inside its trunk. If the tree should blow down, or we should ever cut it down we could tell how many years it had lived.
"Each year a layer of soft green wood grows right next to the bark, and when winter comes this wood hardens until it is like the other wood. So when the tree is cut down we see in rings of wood the number of years it has been growing."
—Zelia Margaret Walters.
