Why do leaves change color?
In fall, because of changes in the length of daylight and changes in temperature, the leaves stop their food making process. The chlorophyll breaks down, the green color disappears, and the yellow to orange colors become visible.
During this time chemical changes may also occur, which form different colors including the development of red anthocyanin pigments. Some mixtures of chemicals give rise to the reddish and purplish colors. In trees such as sumacs and dogwoods, while others give the sugar maple a bright orange.
Autumn foliage of some trees show only yellow colors, or others brown. All the colors are due to the mixing of varying amounts of the chlorophyll residue and other pigments in the leaf during the fall season.
But why do leaves fall?
In autumn, in response to the short days and decline in the amount and intensity of sunlight, leaves naturally prepare to fall. The veins that carry fluids through the leaves gradually close off as a layer of cells form at the base of each leaf. Clogged veins trap sugars in the leaf and promote production of anthocyanins. Once this separation layer is complete and the connecting tissues are sealed off, the leaf is ready to fall.
It helps the tree survive the cold, and dry air in winter. In the warm seasons, like Summer, leaves use sunlight, water, and air to make the tree’s food through photosynthesis. In that process, the tree loses a lot of water. In winter, the tree does not get enough water to replace what it would lose through the leaves. If the tree did not seal the spots where the leaves grow, it would die, so the leaves must not stay on the tree. When spring brings warmer air and fresh water, the tree will sprout new leaves and start growing again.
In fall, because of changes in the length of daylight and changes in temperature, the leaves stop their food making process. The chlorophyll breaks down, the green color disappears, and the yellow to orange colors become visible.
During this time chemical changes may also occur, which form different colors including the development of red anthocyanin pigments. Some mixtures of chemicals give rise to the reddish and purplish colors. In trees such as sumacs and dogwoods, while others give the sugar maple a bright orange.
Autumn foliage of some trees show only yellow colors, or others brown. All the colors are due to the mixing of varying amounts of the chlorophyll residue and other pigments in the leaf during the fall season.
But why do leaves fall?
In autumn, in response to the short days and decline in the amount and intensity of sunlight, leaves naturally prepare to fall. The veins that carry fluids through the leaves gradually close off as a layer of cells form at the base of each leaf. Clogged veins trap sugars in the leaf and promote production of anthocyanins. Once this separation layer is complete and the connecting tissues are sealed off, the leaf is ready to fall.
It helps the tree survive the cold, and dry air in winter. In the warm seasons, like Summer, leaves use sunlight, water, and air to make the tree’s food through photosynthesis. In that process, the tree loses a lot of water. In winter, the tree does not get enough water to replace what it would lose through the leaves. If the tree did not seal the spots where the leaves grow, it would die, so the leaves must not stay on the tree. When spring brings warmer air and fresh water, the tree will sprout new leaves and start growing again.
Written by Ross