Great blue lobelia has many color forms. It can be white or pink. Or it can be a wild variety of shades from entirely dark blue to white, sometimes with stripes or spots.
Lobelias are closely related to the aster family. Many flowers in the aster family have tubular flowers that split almost to the base, then open up to show a long flat limb. Lobelia flowers are also split along their upper side, but only open to show a short lip. This could be a slightly earlier evolutionary stage.