With out a doubt plants have spirts, which if the 'right' person becomes involved with them communication is possible. They are a living breathing organism which can be further deepened by bringing up aura's. (which I wont really get into, just mention it)
The gardens of Findhorn are a perfect example when the right people (not just because they believe but obviously there is some I believe genetic encoding making certain peoples predisposed to light work) do the right job miraculous events can transpire. Here is just a brief overview of Findhorns gardens.
http://www.occultopedia.com/f/findhorn.htm
Pretty interesting...
Now I have undertook my own experiments with plants mainly experimenting with music and physical touch and 'tuning into the plant' (I am speaking of growth not consumtion). I in no way claim to be anything other than what I am, human. The results were obvious.
Now I established that plants have spirts/essences (if you don't believe that, no problem your just not quite 'there' yet), I would hope most people would agree with me when I say people have spirits/souls. Hence the quite common occurence of ghosts/spirits/etc. Now is it really that far fetched to think that the 'spirit' of the plants shows it self to whom it wishes? No. simple
I will push it a little further by saying some psychedelic plants seem to have a stronger essence than other plants. Part of this might have to do with why certain plants are associated with 'entities'. They could be spirits, guardians, or keepers of the plants. Instead of associating this back to ghosts, etc. (which some people don't belive in, which I will never understand) how about associating these 'entities' of the plants with the same type of aspect Guarding angel or religious entities are to humans.
I hope I wrote this clear enough...
But alas science and 'rock' solid data is what it takes for some skeptics to believe, but believing is just half the battle...