Plants were a variety of life forms found on many planets. Some plants were sentient, such as the Bush creature, the Cyclamen of Preplanis, and the flora of Tybo's planet. ("The Raft"; "Attack of the Monster Plants"; "The Great Vegetable Rebellion")
Sybilla and her children traveled to various planets breeding carnivorous plants. ("The Space Croppers")
Professor Robinson and Major West worked on a purifier to kill a blight that had affected plants used for food. ("Space Circus")
Tybo was a carrot that vilified animal life. He had the ability to transform animals into plant and attempted to do so to the Robinsons. ("The Great Vegetable Rebellion")