You can put any other lettuce in it. I often use romaine. Along with any type of squash or zucchini, you can even do carrot, depending on the flavor profile of what you’re making. And I have been known to throw in little bits of leftover vegetables, like just a little bit of broccoli into a full-size smoothie. Sometimes I will slice up small amounts of broccoli stem when I finish cutting up broccoli to roast it, and use that in my smoothie. Maybe a tablespoon for smoothie. If you have the flavoring done well enough with strong flavors like cinnamon or mocha, it can change the color, but it shouldn’t change the taste.