From the CO2Science archive: This week’s plant is native to Ontario and the northeast US and goes by the pleasant name of Spring Avens. And we can’t find any mention of people blasting it as an invasive weed or saying it’s toxic to horses or any of the usual complaints we read about the world’s plants. So here’s to Geum Vernum with its dainty little flowers. In 2013 a pair of experiments showed that an additional 300 ppm CO2 in the air caused an average 35.5 percent increase in its growth. Go Spring Avens.