To the original questioner:
If you do a Google search on Rosaceae, you will probably come up with one or
more Web sites which give you the "diagnosis" for the family, that is, its
characteristics and how it differs from other plant families. You could get the
same information for the genera by searching on Malus and Prunus. However, this
information is so full of technical jargon that it probably would not be of
much help to a layman. My advice is still, go outside in the spring, watch the
buds unfold & the flowers bloom, and use your eyes. Compare the Rosaceae with
plants from some other families, like lilacs and azaleas. You will learn much.
Iris,
Central NY, Zone 5a, Sunset Zone 40
"If we see light at the end of the tunnel, It's the light of the oncoming
train."
Robert Lowell (1917-1977)