Leaf Senescence & Abscission (revised)
University Outreach Publication
Formation process and associated leaf fall in development of fall leaf color in trees.
Spring flower colors are raised in fall to crown the trees. Many of the pigments are the same but the
colored containers have changed from dainty petals to coarse, broad leaves. It is living leaves that reveal in their
decline and fall last summer’s results and next spring’s promise. The living process in a tree generating autumn
colors is called senescence.
Senescence is the pre-planned and orderly dismantling of light gathering structures and machinery inside
a leaf. Part of senescence is the development of a structurally weak zone at the base of a leaf stock or petiole.
Live cells are needed in the leaf to unmask, manufacture, and maintain the tree pigments we appreciate as
autumn colors. Fall coloration is a result of this positive life process in a tree. Freezing temperatures kill leaves
and stop the senescence process with only decay remaining.
WSFNR08-33
Dr. Kim D. Coder
September 2008
Warnell School, University of Georgia
Athens, GA, USA
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WSFNR08-33
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