Why Do Leaves Fall Off Trees?

Why do leaves really fall off trees? It's not the wind. It's not the cold. It's because trees use 'scissors' to cut their leaves off. Around this time of year in the Northern Hemisphere, as the days grow shorter and colder, those changes trigger a hormone in leaf-dropping trees that sends a chemical message to every leaf that says, in essence, 'Time to go! Let's part company!'

Once the message is received, little cells appear at the place where the leaf stem meets the branch. They are called 'abscission' cells. They have the same root as the word scissors, meaning they are designed, like scissors, to make a cut.


1 comment:

  1. the question is wrong, or the answer.

    The question that would work for this explenation would be. "How" do leaves fall off trees.

    The answer to the question "why do leaves fall off treas". I don't know, but could be something like; to protect the tree from freezing, or to make a protective blanket for the fruits that fall off a little earlyier.