Plus I've read all cultures troughout the ages have interacted with plants as intelligent beings.
I for one agree with you on many levels. Part of the problem here is in the definition of CONSCIOUSNESS.
If you consider that Everything is consciousness, and composed of consciousness, or rendered by consciousness, existing within consciousness SPACE, then everything possesses CONSCIOUSNESS. And every smaller peice of consciousness contains ALL the potential of the whole (fractal in nature), just as every cell in our body contains all the information of the entire body. Tom creates a stricter definition of what can be called a consciousness entity. A fish has more decision space than a clam and possesses greater mobility, response capabilities, and greater interaction with its environment, but does it possess MORE consciousness? Or simply different type of consciousness?
Tom discusses many varied types and degrees of consciousness in his book. Including some types of "Elemental consciousness" (which, I found, possessed fascinating implications) and even "Group souls" So while a single clam, a SINGLE tree, or a blade of grass might NOT be classified as a conscious ENTITY, a group of clams, a forest, or an entire FIELD of grass MIGHT (under TOMs definition). But you are free to build up your own BIG TOE and develop your own definition of "what constitutes consciousness?"
Remember we exist WITHIN CONSCIOUSNESS (according to MBT) That would infer that everywhere we look, we would see consciousness. And we are all parts of the SAME consciousness that we exist within. That would mean that there is only ONE consciousness in the universe, and it is you, and it is me, and it is the trees, birds, oceans, rocks, grass, and even the furniture.
But Tom leaves plenty of room for us to discover our own truth. And he leaves plenty of room for all things and all expressions of truth and consciousness. It is, after all, a BIG TOE. not a little TOE. It is not exclusive, it is INCLUSIVE.