When a branch or even a stem is cut from a deciduous tree, why do the leaves stay attached to stems?
http://en.wikipedia.org/wiki/Abscission
Special cells attach deciduous leaves to stems. In autumn, decreased sunlight triggers the production of chemicals that breakdown the walls of the attaching cells. This results in the leaves falling off of the stems.
If the stem is removed before the cell wall destroying chemical forms, the stem and attached leave die, but the leave remains attached to the stem.
DISCOVER FOR YOURSELF
Green leaves attached to a stem that is broken from a plant will die and turn brown. But the dead leaves do not fall off the stem. Try it. Collect stems with leaves and create a leaf arrangement. Decorate the container and place it where the leaves can be observed but not disturbed for 3 or more weeks.
Advanced Learners: Research These Words: abscission layer, petiole
