Lean
The
trunk is a physiological and structural connection between
the crown and root system. Serious trunk lean can cause
structural problems and may cause the tree to fail. This
is especially apparent if some soil cracking and/or uprooting
is also observed. Some species that are on the border between
being either small trees or tall shrubs have a tendency
to exhibit lean. This can be the case with Russian Olive,
Serviceberry, French Lilac, Hawthorns, Japanese Maple and
Staghorn Sumac. However, the leaning trunk of such species
is usually not serious.
Three classes of leaning can be recognized
using the following rating: