I also happen to know that in some places they put Coca leaves on it too. But only in the Hot water version. Usually on higher altitudes because Coca does facilitate the breathing by improving the oxygen absorption or something similar... at least that's the excuse they use, I'm not buying it completely.
To anyone that may feel weirded out, coca leaves are sold as tea, or fresh to eat with coffee in various parts of Central and South America. Adding them to an infusion like "mate" was an unavoidable next step.
Peace