oh yes, they're smart
"The main driver of evolution in plants was to survive the massive removal of part of the body,” said Mancuso. “Thus, plants are built of a huge number of basic modules that interact as nodes of a network. Without single organs or centralised functions plants may tolerate predation without losing functionality."
"we depend on plants not only for many of our raw materials and our food, but also for the oxygen we breathe and, increasingly it seems, the rain we require. Plants drive many of the biophysical forces that make the Earth habitable for humans - and all animals."
https://www.theguardian.com/environment/radical-conservation/2015/aug/04/plants-intelligent-sentient-book-brilliant-green-internet