Lost In Space:
The Great Vegetable Rebellion
Original Broadcast: 28 February 1968
 
Dr. Smith plucks a flower on a planet. For the murder of innocent vegetation, he is sentenced by the ruler of the planet, a giant carrot named Tybo, to be turned into a plant himself. Soon, John, Maureen, Penny and Don are inprisoned in a greenhouse/forcefield in preparation for their transformation into plants.
 
If you've ever seen the LIS cast at an appearance, you know how they feel about the episode (and if you haven't, let's just say they ain't waxing nostalgic). The sad part is, that in spite of the pure unadulterated dreck that passes as a script, its one of the few later episodes that the entire cast actually is involved in.
 
We've got mad scientist/giant carrots, Smith/zen spouting celery, Penny/flower child. Judy gets to diagnose environmental control problems, gets threatened by a giant carnivorous Christmas Cactus, runs around the jungle with a machete, and climbs a vine up a sheer rock face in lavender high heel boots. Let's see Jim Kirk try that!