The writer for the book is rumored to be David Whitaker, but the writing style is inconsistent with Whitaker's style. Truth is, the book is entirely uncredited, and since Whitaker died without, apparently, having taken public credit for the work, we will perhaps never know who's responsible for this volume.
Synopsis: The First Doctor returns alone to the planet Birr. There, he discovers the planet almost lifeless, devoid of all its vegetation, and of its intelligent plant life, the Verdants. He is almost immediately captured by the Rostrows, a group of scientifically advanced beings. They landed on Birr to conduct a planetary survey, and have since been unable to power up their ship to depart. Lahk, their leader, asks the Doctor to investigate the problem, and commands one of his subordinates, Duh, to accompany the Doctor.
On their way to the engine room, Duh shows the Doctor some of the samples they collected, which include some of the vegetation of the planet. The Doctor is intrigued to hear that all of the plant life simply disappeared when the survey team made their cuttings. Suspecting something "bigger" going on, the Doctor and Duh leave the ship in search of the missing plants. After some difficulty, they find the plants deep beneath the planet's surface, where the Doctor and Duh are granted an audience with Phlege, leader of the Verdants. Taking the cuttings was interpreted as a hostile act, so the plants retreated below the surface and put a dampening field around the Rostrow vessel. The Doctor and Duh are able to convince Phlege that the survey team meant no harm, so Phlege and his Verdants return to the surface and restore all power to the Rostrow vessel. The Rostrow, and the Doctor, are thus free to go.
Notes: Some sources indicate the writer of this story was David Whitaker, others say that's complete rubbish. But the most honest opinion is probably that no one knows for sure who wrote this story.