The idea of plant vision isn't quite as ridiculous as it may first seem.
Some cyanobacteria can "see" by using their entire single-celled bodies to focus light. A little like tiny swimming eyeballs. The idea that higher plants could contain similar structures (called "ocelli") has been hypothesised by botanists for some time. Among others, Francis Darwin (the son of Charles Darwin).
Here's an article from Scientific American with more info: