I found the Dover book I was thinking of.
Floral Engravings for Artists and Craftspeople.
It has engraving of plants and leaves. It is good for finding new ideas for leaves to adapt with scroll.
Steve
PS.. I don't think I have the following two, but they might be good too:
http://store.doverpublications.com/0486269574.html
http://store.doverpublications.com/0486290743.html