Gardenizen

Gardenizens were eco-drones in Earth's future, designed to offset the people of Britain's carbon footprints. About four feet tall, these mobile-greenhouse-like tripods each housed a plant in a dome above their stand and were assigned to everyone. Some people choose to give them individual names (like Arthur) but ultimately each was linked to one huge, super brain, a master plant that resided in a control room at Kew Gardens in London. For a while the Gardenizens rose up against the humans who had created an unsustainable existence on the planet. The Doctor, detected as an outsider and not human, was able to open discussions and a truce was agreed. (DWAM: The Garden Rebellion)