From the CO2Science.org archive: Erica Tetralix is by all accounts a very pretty little flowering perennial that grows in western Europe, especially in wet, boggy areas. And as far as we know it has never expressed any overt Nazi sympathies. Unfortunately the Nazis were fond of it, and a song about it (“Erika”) became one of the most popular marching songs of the Wehrmacht. But we won’t hold that cultural curiosity against it. Instead we will note that in 1998 there were four experiments showing that an extra 300 ppm CO2 boosted its growth on average by 23.8%. Just remember, if you’re the kind of person who also talks or sings to plants, be careful what you sing.