The Robinson Family had a number of encounters with members of the vegetable kingdom beyond the plants growing in their hydroponic garden. In fact, there is a distinct theme of plants seeking to take over or even annihilate the crew of the Jupiter 2 running through a number of shows over the three year run of Lost in Space.
Two notable examples of plants bent on the utter destruction of the Robinsons (or at least a few of them) are in the episodes “The Raft” and “The Space Croppers,” both in season one. In “The Raft” Dr. Smith and Will return to Priplanus after an attempt to reach earth on a ‘space raft.’ They land at a sufficient distance from their encampment that the surroundings are unfamiliar to them and they do not know where they are. As they begin to move around, they are menaced by the local vegetation, and one suspects that it is in fact somewhat sentient. Finally, a “plant man” appears who clearly means them no good.
In “The Space Croppers” the crop referred to in the episode title is plants that, whatever their benefit to their sowers, consume every living thing in their path; the process itself is quite gruesome according to the description given to Dr. Smith by Sybilla.
Clearly sentient plant life intrudes upon the Robinsons most obviously in the notorious “Great Vegetable Rebellion” where Tybo and his assistant Willoughby (who is part plant after a celery heart transplant) seek to transform the entire crew of the Jupiter 2 into plants, an example of the assimilationist agenda of some plant life in the show.
The earliest episode with the theme of assimilation by plants is in season one. The unnecessarily silly title, “Attack of the Monster Plants” belies a truly good episode, and one which offers Marta Kristen more screen time and more scope to exercise her talents than almost any other episode in the series. The plants that star in this episode are able to duplicate any object with which they come into contact, and produce a copy of Judy with which they intend to infiltrate the Robinson encampment.
The third season episode “The Flaming Planet” features what Dr. Smith insists is an orange tree (he seems forever to be identifying species of terrestrial plants and birds on alien planets). Radiation encountered during their flight mutates the shrub into a giant, sentient and motile plant that has an emotional attachment to Dr. Smith. Although not malicious, it causes no end of trouble to the Jupiter in flight; a solution to their problem is found when the lone remaining Sobram warrior on a nearby planet needs a new foe to battle, and the plant’s interesting characteristics make it an admirable opponent for him.