Sleeping grass makes me think of nature movies again, only I'm thinking of ones like Planet Earth, which show amazing time-lapse video of forests where new plants spring up in a matter of hours, or where the leaves change from green to gold to red in a matter of days. Those fast-forward movies do a pretty good job of making plants look a lot like animals, don't they? They're not sentient beings; they're responsive, they sense, they move. And in this case, with sleeping grass, we can clearly see it.
I wonder why more plants haven't evolved to employ such quick reflexes?