• Question: Why do leaves change colour in the autumn?

    Asked by smileyabz to Arttu, Ceri, James_M, Monica, Philip on 15 Jun 2011.
    • Photo: Philip Dolan

      Philip Dolan answered on 15 Jun 2011:

      Deciduous trees (that is the type of trees that loose their leaves) allow their green leaves to die. I’d imagine the precise way they allow this to happen (i.e how the chloroplasts in the tree’s leaf cells die) allows the leaves to change colour to orange and yellow etc, before finally falling off the tree. They do this because in the winter there is not so much sunlight, and the tree can survive the cold weather much more easily if it doesn’t waste energy keep the leaves alive (especially since there isn’t any sun for them to perform photosynthesis on).

    • Photo: James M Monk

      James M Monk answered on 15 Jun 2011:

      In addition to what Philip says, I think the trees draw the chlorophyll from their leaves down into the roots rather than waste it in the leaves when they fall off. Chlorophyll is the green coloured substance that converts sunlight into oxygen and food for the plant – once the chlorophyll is removed the leaves turn from their green colour.

    • Photo: Ceri Brenner

      Ceri Brenner answered on 15 Jun 2011:

      nice, think i’ve just learnt something new there too

Comments