Although it is an old question, it is worth noting that some individuals may be able to communicate with plants or animals. Do not forget, we are the children of plants, after all. We need them, they do not need us. They were here first, and from a biological perspective they are identical to us in the way that they replicate and function. The difference is that they obtain energy from the sun - that important intermediary step is what unlocked our futures, as intelligent, reasoning human beings.
That being said, although plants, flowers and trees do not move or speak, they are in constant communication with one another, silently relating temperatures, pressures, assimilating communications from other species of plants, planetary positions, habits of nearby life. They are quite tuned to the apparation of life itself, and even conscious of the loss of any nearby life.
As for 'intelligence' it would difficult to prove, as they have no apparent brain. However, they evolved along a different evolutionary branch, long, long before us, and their consciousness may consist of electrical and chemical signals.
Many cases of schizophrenia are the confusing interferences from the communications of plants and animals. Certain humans may have developed the ability to decode or receive these communications over the millions and millions of years that our 'cousins' have been here, shielding and nourishing us.
Although this may not be the case in this instance, it is definitely something to consider. The story you have related of the field and the trees strikes me as a possible solution to this strange problem.
This is the reason that old people build gardens and spend all day tending flowers and their yards. Plants are special and not to be feared or dismissed as lifeless ornaments.