From the CO2Science Archive: The plant Conium maculatum earned its place in history as the deadly brew drunk by Socrates to comply with the death sentence passed on him by an Athenian court. And that once-famous event occurred long before all the extra CO2 was in the air so philosophers beware. According to CO2Science in 2007 there was an experiment in which hemlock was exposed to 300 parts per million extra CO2 and its biomass increased by 21 percent as a result. There was only one such experiment and we hope this doesn’t mean the scientists involved got their tea cups mixed up.