Got some different coffee species to try!
Excelsa and Liberica are maybe different varieties of the same species, but they are pretty different from each other so coffee people (unlike botanists) treat them as separate species. Unlike arabica and robusta which are shrubs, these can be giant towering trees!
Excelsa apparently accounts for 7% of the commercial coffee yield in the world, so it's a not-so-distant third to the well known arabica and robusta.
Liberica on the other hand is harder to find - this bag even says "endangered species" on it! I haven't looked in the bag yet but the beans are supposed to be comically large and also asymmetrical.
I think both of those have moderately high caffeine content, but I'm not too sure.
Then there is eugenioides. The king of coffees, C. arabica, is actually a hybrid where one of the parent species is robusta, C. canephora. The other hybrid parent is eugenioides. So while arabica gets its high caffeine content and bold flavor from robusta, it gets its sweetness and complexity from its mild, low-caffeine parent, C. eugenioides. I think it's about half the caffeine content of arabica or even lower.
I just made a pot of excelsa and it's definitely interesting. Smells similar to robusta with strong smoky, woody, and "barnyard" aromas, and the taste is powerful. It actually has plenty of acidity even though this is a dark roast.
Definitely one to put hair on your chest!