You can create separate categories to place them in, one for each class. Check my profile to see how I create different categories.
When you click on your list from your profile page, on the left side in the blue section, you will see the "View and manage your List". Click that and you'll see your current list with a box below "To create a category, enter a new category name below:"
Once you have your categories in place, you can now edit your list and check off the appropriate category you want your plants in.
