From the CO2Science archive: No not Arabic gum, the Gum Arabic tree, also known as thorn mimosa, Egyptian acacia &c &c and formally as Acacia nilotica Willd. although it has been renamed as Vachellia nilotica. Whatever you want to call it, and yes it is more Latin, these trees grow in the Middle East, Africa, India and Australia. And they seem to be remarkably useful, providing us with valuable lumber, cattle feed and even medicinal supplements. And we return the favour by providing it with CO2. From 2004 to 2010 there were 11 experiments showing that an extra 300 ppm CO2 boosted growth by an average of 241.5 percent. By gum.