From the CO2Science archive: Trifolium repens L. [White Clover] This week we honour St Patrick by looking at the effect of CO2 on the humble clover plant he is said to have used to teach the finer points of Christian theology to the Irish Celts. From 1985 to 2010 there were 49 experiments that found clover adds an average of 64.9% more biomass when exposed to an additional 300 ppm CO2. More CO2 means more clover, happier horses and cows, and busier bees. It’s like spreading the luck of the Irish all over the world.