Well, Epi. parkinsonianum flowers are large, but I never had the curiosity to measure them. When these opened I thought that they seemed a little larger than the flowers from another plant I grow and decided to check it out: 7.5" across!
I grow two plants of this species, one mounted on a tree fern plaque and this one, which is planted in a small plastic pot filled with tree fern fiber. In this case the roots are mostly aerial while the mounted plant has most of them wrapping the mount and only a few in the air. The potted seem to grow slower than the mounted and the reason is undoubtedly the nutrients the tree fern release on a constant basis, nutrients that are not available for the potted, although I fertilize it.