The lists feature doesn't currently work very well for unnamed seedlings. plantladylin has the right idea to add the main Hemerocallis entry and describe your seedling in the notes. But you can only do that once since the system doesn't let you add the same plant to your list twice.
It's something I'm working on for a future update to the feature.
Here is the main entry you want:
Daylilies (Hemerocallis)
Over on the left, click on the blue button to add it to your list. Then you can edit it in your list and add your description.
