Ashley, I use XFrog with Cinema4D quite often. Your plants should have a bark and leaf texture applied in XFrog. The bark texture is usually assigned to one or two materials depending on plant type and branching. The leaf texture and alpha map are assigned to the leaf material. The meshes are already UVmapped. Just manually reassign the texture maps to the materials in Poser. Be forewarned, XFrog meshes can get quite high in polygon count.

Mike K