Every flower has got its own meaning..irises mean "good news"..so, Clark, why don't you take a chance and tell Lana the reason why you believe in life on other planets?!?
Just imagine for a moment, if you will, you are kissing the one that you are madly in love with. Then, the moment the kiss is done, all she says is "do you believe in life on other planets." Maybe that is something that can be brought up a few minutes after the kiss because that is a weird way to try to keep a romantic mood alive.