descend; become lower
Depending on the environment. if the branch has fallen in a dry environment it won't rot, but if the branch has fallen in a wet or damp environment e.g-rain forest the branch will rot.
Limb, or bough.
If you are looking for the crossword puzzle answer, another name for fallen rock debris is scree.
Enforcer
Congress
A tree branch is called a Bough.
limb, bough, scion
Branch is one and bough is another.
Senate and house of representitives
scar
cork layer