To "see," according to ecological psychology, is not to form a picture of the world in your head. It stresses that patterns of light on the retina change relative to your movements. It's not the brain that sees, but the whole animate body. The result of "seeing" is never a final image for an internal mind to contemplate in its secret lair, but an adaptive, ongoing engagement with the world.
Plants don't have eyes exactly, but flows of light and energy impinge on their senses and transform in predictable ways relative to the plants' own movements. Of course, to notice that, you first have to notice that plants move.
