Journey Through the Secret Life of Plants. This two CD set from the Motown legend was originally released in 1979 and was the follow-up to his hugely successful Songs in the Key of Life album. This mostly instrumental album was the soundtrack to the documentary the Secret Life of Plants, directed by Walon Green, which was based on the book of the same name by Peter Tompkins and Christopher Bird. The album was chiefly written by Stevie although it does include collaborations with Syreeta and Michael Sembello. 20 tracks. Motown.