The plant recorder was one of several inventions that was part of The Future of Law Enforcement for the Hill Valley Science Expo of 1931. At the press of a button, a person's voice could be recorded and played back.
While taking a look at The Future of Law Enforcement exhibit, Marty McFly, a time traveler from 1986, noticed the plant and asked how it would help enforce the law. Officer Danny Parker, who was hosting the exhibit, demonstrated the recorder, pressing the playback button and causing the device to repeat Marty's question while at the same time answering it.Later, in order to discredit Edna Strickland to preserve the future, Marty took a regular potted plant from the Future Furnishings exhibit and replaced the recorder with the actual plant. He placed the recorder in the Phone Booth of the Future and called Edna from Future Furnishings, pretending to be Carl Sagan in order to trick her into admitting any possible wrongdoing she might have committed. Edna admitted to have been the speakeasy arsonist and the confession on the recorder was enough evidence for Officer Parker.
Marty used the plant recorder again in 1931B to help a time-displaced Edna Strickland into regaining her repressed memories.
- It is possible to make the remainder of "Episode 5" unplayable if the plant recorder is left in the Phone Booth of the Future after exposing Edna, but before finding Emmett.