Leaves stop taking up water in autumn, preparing for winter dormancy. This lack of water to each leaf causes a very important chemical reaction to stop - photosynthesis - which is the food-producing combination of sunlight, water, and carbon dioxide. Chlorophyll depends on photosynthesis and disappears from the leaves. Chlorophyll is the green you see in the leaf.
Once the overwhelming chlorophyll color is removed, true leaf colors will dominate over the receding green pigment. True leaf pigments vary with the species of tree and thus the different characteristic leaf colors. And because true leaf colors are water soluble, that makes the color disappear very quickly after drying out.
Here is an illustrated step-by-step of how three major pigments color leaves in fall...
USFS Illustration
Comments
Hello ,
I came across your page while looking for help with a beloved maple tree, I was wondering if I could pick your brain???LOL
I am in Canada and have many trees but one with (Red maple, has burgendy leaves all summer) anyway, it’s wonderful leaves are covered with what looks like a dusty/powdery looking or ashy coloured looking dry mold ???,, the tree is vibrant and seems healthy but the last two years it comes back , I want to save it it is 12 years old , it is a large tree about 25 or so feet high with a great deal of leaves . Anyway if you have any advice as to rid this problem I would greatly appreciate it , you may email me at the given add. if you have time .If not thank you for your time . You have a great day .
Thank you
lindsay
Hi, Has anyone answered you yet? I am no specialist but I am into trees, and growing things in general. It sounds like powdery mildew to me. I get it on my lilac and a few crab apples in the most humid days of summer. It doesn’t seem to bother the plants at all so I haven’t done anything about it but I am sure they have a spary for it.
I have never seen the science of color change in a leaf broken down to a 3d scaled model. This is very unique and interesting. Certainly this provides a great depth of understanding.
You didn’t expain as to what triggers the leaves response in loosing chlophyll. Can you explain this?