I suggest planting some herbs like rosemary, sage, thyme, basil, or lavender. Those are also edible so if you ever find yourself wanting to spice up a dish you made or want some tea you already have them in your room. Aloe Vera is also another good choice. Not only does it help clean the air, it is excellent for burns and mild rashes. I also suggest getting a cactus if you're looking for something that's a little low maintenance. Succulents are also another good choice.