The real issue here is not what category this part/design should be placed under.
The real issue is the hierarchical design of the catalog that forces all parts
to live in only one category. Some pieces (such as this one) really do need to
exist in more than one category.
The alternative to having n categories, is to do away with categories entirely,
and instead provide tags for each part. This part would likely have tags for
tree, palm, and bar. I'm not trying to redesign the world, but pointing out
that the existing design has shortcomings (which is really the entire point of
this thread).