Falling Tree Leaves: Leaf Abscission
University Outreach Publication
Trees loose their leaves by design. When leaves become inefficient and unable to produce food and growth regulators, a process of shutting-down and sealing-off begins. Trees shed many parts besides leaves, including fruit, flowers, bud scales, trichomes, twigs, and bark. Leaf abscision is the best example of the process of tissue shedding in trees.
The mechanism of tissue shedding has two components, active and passive. The active part is development of an abscission zone. Tree tissues, like leaves, are actively prepared for removal through biologi-cal and mechanical means. The passive part of tissue shedding is development of structurally weak areas along which force can be concentrated and tissues torn away by the environment. In other words, some tissues have cells which are actively broken apart, while other tissues have built-in weak zones which allow these tissues to be ripped away.
(FOR99-025) December 1999
Kim D. Coder
1999
University of Georgia School of Forest Resources
Athens, GA
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Abiotic Factors, Aesthetics, Children and Youth, Compartmentalization (CODIT), Landscape Ecology, Photosynthesis, Recreation, Biology (tree)
International
Abscission, Fall leaves, Leaf abscission, Leaf fall
