There are several different kinds, Chards, Kale, Collards, and all the different lettuces. Chard and Kale have several different varieties as well. Check out your local Whole Foods.
Using Romaine lettuce is a great way to change things up a bit. Collard greens, mustard greens, and Bok Choy are great substitutes as well. Bok Choy is really great in stir frys.
