Looks like I'm almost there. Exported the plant .obj. and made the 2 material groups with the Grouping Tool. But when I applied the Xfrog textures this happened. Looks the same rendered. The leaf and bark (stem) textures are .png files. When opened in Photoshop, the edges are selected and I can copy and paste just the leaf/stem (separate from the background). Things like transparency maps come to mind, I have seen leaves on other poser plants with this type of set-up, but don't know the ins and outs of how they work.