My first recommendation is

The Secret Life of Plants: A fascinating account of the physical, emotional, and spiritual relations between plants and humans...

By Peter Tompkins and Christopher Bird

You are going to be stunned by how alive plants truly are... the second half is a little dry though...

"Once in a while you find a book that stuns you. Its scope leaves you breathless. This is such a book." John White, San Francisco Chronicle

Is hard to find but can be ordered though...

Publisher: Perennial- An Imprint of HarperCollins publishers