Ep 23. The Great Vegetable Rebellion

Doctor Smith realizes he may one day need the Robot's good will. So he commandeers the space pod and descends to a planet home to vegetation, but no animals. His goal: a few flowers for the Robot's birthday party! But on this planet, ruled by Tybo, vegetables are king, and harming them is a capital crime. For his crimes, Tybo intends to turn Smith into a plant! And when the Robinsons descend looking for their errant passanger, and begin hacking their way through the dense foliage, well, Tybo soon devises new forms for them, too!