Arugula is a cruciferous vegetable and a cousin of broccoli, cabbage, and kale.  In the supermarket, you might find “baby arugula”, which farmers harvest early.  As the arugula ages, the leaves become more peppery, spicy and even bitter.  Wild arugula tends to be the most pungent. 

For my Hummus Quesadillas, I prefer the rocket or sylvetta variety, but any will work.  In fact, my kids prefer the baby arugula since they don’t like bitter greens.