This is a very important question. Elsewhere @Manpreetheersskp, @Arunan and I were discussing, the role of brain and nervous system. For some sea squirts, which do not need to move, they eat up their brain. Now that plants do not need to move, it makes sense to me that they do not require a specialised organ called brain!
@drishtantmkawale, Why do you think plants should have a brain?
But, do plants stop sensing!?
@Manpreetheersskp do sea squirts stop sensing? 
-DP