From the CO2Science archive: We have a possible mixup in the CO2Science library, the first we have encountered in what is otherwise a meticulous online resource. Pteridium revolutum is the Latin name and the Common name given is Hairy Bracken. But on the interwebs, Hairy Bracken is Pteridium aquilinum, common throughout western North America, while Pteridium revolutum is Wooly Bracken or South Asian Bracken and is common in India and, as the name suggests, South Asia. Pteridium aquilinum has its own entry in the CO2 Science archive which shows that from 1999 to 2008 there were 4 studies showing that an extra 300 ppm CO2 boosted the fern’s growth by an average of 45.3 percent, while for its Hairy cousin, three experiments in 2008 showed that an extra 300 ppm CO2 boosted growth by an average of 49 percent. So whether your fern is in western North America, South Asia or probably anywhere else, or even if you think Hairy Bracken should be a comic-book character not a plant, it wants more CO2.