The Phantom Orchid, Cephalanthera austiniae is endemic to northwestern North America. This plant has no chlorophyll and is entirely white. Incapable of photosynthesis, it is entirely dependent on mycorrhizal fungi for its nutrition. Since the fungi receive no benefit from this relationship, this is not a mutualism but rather a case of a plant parasitizing fungi.
More about this orchid: Encyclopedia of Life
Image by Earl Nance via CalPhotos