Damp or waterlogged soil is
caused by poor drainage.
The most common cause of this is clay soil although other features
can be responsible.
Most plants don't like waterlogged conditions and those that
do have more in common
with aquatic plants than land plants.
Plants for Boggy Ground:
This is just 3 examples of plants that will grow in what is
far from ideal growing conditions.
Most pond marginal plants will grow in boggy ground but converse
is not necessarily so.
Click this link for list of Aquatic
Trees suitable for badly drained
Click on the links below for more detailed information on problem
and for lists of plants to grow in them