What order do leaves on a tree change color? Is it that the closer a leaf is to the trunk of the tree, the faster it changes? Further from the trunk? Leaves that receive more light? I’ve tried looking this up but either I cannot find an answer for this, or maybe I am just not asking the right question
Comments
[removed]
Unfortunately, like so many things, the answer is “it depends.”
(And, to help you in your future searches, the term you’re looking for is “leaf senescence”.)
Leaf senescence, the programmed dismantling and death of leaves, is controlled by a lot of factors…age, environmental stress, damage, sugar consumption, chemical signals from elsewhere in the plant, etc. And consequently, the pattern of color change changes based on what’s triggering the leaf senescence.
If the leaves are senescing prematurely because of airborne stress (drought, for example) then leaves getting the most light will likely be the first to change. If the stress is coming from toxins in the soil, the leaves will most likely all change at the same time. If the stress is coming from infection, the leaves may change in patchy or irregular patterns.
But if we’re looking at the programmed leaf senescence of plants that shed their leaves every autumn, it still depends…on the species. In an oak, the whole tree turns color at the same time. In a mature beech reaching the top of the forest canopy, the bits exposed to the sky will change before anything else…then generally the leaves turn top-to-bottom. The leaves of the mountain ash, however, turn bottom-to-top. You’ll find nice pictures of all these examples in this paper on visible symptoms of stress factors in foliage. (See Figure 2).