Following today's earlier post on the intelligence of cats and parrots, I was reminded by Michael Marder's appearance last year on the Philosopher's Zone (link HERE) that plants ought to be part of this discussion as well.
Other than the documentary below After Nature readers may be interested to listen to Stephanie Theodorou and me on the Philosopher's Zone discussing the emotional lives of animals, HERE.
The intelligible form of semiotic expression - emotional, social, rational - is varied and yet found nearly throughout all of the natural world.