From the CO2Science archive: This grass grows pretty much everywhere and even though the seeds are supposedly edible it’s generally considered a weed. Not only does it spread rapidly, its names also seem to multiply rapidly. It’s known variously as goosegrass, Indian goosegrass, yardgrass, wiregrass, crowfootgrass, silver crabgrass and, formally, Eleucine indica (L.) Gaertn. Whatever it’s called, including “that wretched weed again”, it likes CO2. Between 1984 and 2006 there were 6 experiments showing that an extra 300 ppm resulted in an average 34% additional growth, and 2 experiments showing an extra 600 ppm yielded an extra 48.5% growth.