What is a mythical herbal- themed entity?

I am looking for an entity akin to nymphs, dryads, etc that has a healing or herbal theme. I am NOT looking for a deity (god or goddess) or an individual of myth, but a mythical 'species'. I need ones that are medieval-related. The 'Witte Wieven' lore, or wise/white healer woman, is a good example - I need others like that. I need actual lore, not from games or books.