Parenchyma Abscission Layer

The abscission layer, a barrier of thin-walled parenchyma cells, develops across the stem (or petiole) at the base of a leaf, flower, or fruit as it approaches the time of falling from a plant. Abscission is the process that should be recognized for creating the beautiful autumn colors of deciduous trees in temperate regions, and this specialized layer acts as the breaking point for separating the plant from its terminal appendages.