Stevie Wonder's follow-up to his successful, sprawling album "Songs in the Key of Life" baffled many critics and fans.

"Journey through the Secret Life of Plants" consisted mostly of instrumental tracks with only a few vocal cuts. Even though the album wasn't very well received, it still hit number four on the Billboard charts, an indication that Wonder's popularity might have made people's curiosity trump the bad reviews.

Still more curious was the album's origins.

Director Walon Green's 1978 documentary The Secret Life of Plants used fast-motion photography and lie detectors to explore the theory that plants respond to stimulus on an emotional level. Green supposedly gave Wonder, who is blind, extremely detailed, shot-by-shot descriptions of the film to help him write the score.