In many countries, especially in the west, as autumn approaches, the leaves of some trees change color.
It changes from a green to gorgeous hues of red, orange and brown. And then after this marvelous show of beauty, the leaves fall. The tree stands without leaves, just a skeletal of branches until the arrival of spring.
Why does this happen? Why do leaves fall from the trees in autumn? The phenomenon known as the fall? Is it the winds? Or trees deliberately shed their old leaves? Maybe they are like you when you get bored of old clothes and want to get new ones or maybe not.
Leaves are the food factories of the plant. They need water, sun and carbon dioxide to make food. In the food making process leaves lose a lot of water through the tiny openings called stomata. All goes well in summers. The tree even manages to store some food in the form of starch. In winters, there is dearth of water. If leaves make food, they will lose more water than they take in. That way eventually the plant will get dehydrated and die. So, it’s a good idea to get rid of the leaves in winters. That is why leaves fall. Deciduous trees lose all their leaves for part of the year. Maple, poplar, oak are all deciduous trees.
The process through which trees lose leaves is a very intelligent one. It’s called ‘abscission’. As days become shorter in winters, the tree starts drawing all the nutrition from the leaves including chlorophyll to store it for future. Then tiny cells appear at the spot where the leaf stem meets the branch. They are called “abscission” cells. Abscission and scissors are both derived from Latin word scindere which means to cut. Within a few days, these cells become big and swollen enough to bump the leaf off the tree!
But remember that the trees need leaves again in summers. The spots from where the leaves had fallen get sealed by the tree, and when spring arrives new leaves sprout from the same spot.