Dumor3D over at Daz has a beautiful lavender-colored rhododendron. I don't think it has materials for Poser or if there's a way to get it in the program, but I'd think a person could easily take the textures maps and create a material set for an obj file. I've had the rhododendron for a while and it looks fantastic. It is fairly detailed and looks great close-up.

Here's a link to Amaranth's image where she uses the rhododendron: https://www.renderosity.com/rr/mod/gallery/?image_id=2692841

It's too bad Lisa didn't have a rhododendron/azalea product. Her work was wonderful. I'm also surprised Flink has never created an azalea/rhodo set.