So, my horizons were recently broadened when I discovered some relatives to yerba mate that are growing in popularity.
[Guayusa](http://en.wikipedia.org/wiki/Ilex_guayusa) and [Yaupon](http://en.wikipedia.org/wiki/Ilex_vomitoria) (unfortunately named *ilex vomitoria*). The latter of which is actually native to the United States, which I find intriguing.
I expect to receive a shipment of Yaupon in a couple of days, so I'll brew some up and report back.