For the plants below links to PubMed and the USDA Natural Resource Conservation Service are provided. At the time this list was made, these species were poorly represented in the PubMed database.
Achillea millefolium (Yarrow)
Agastache foeniculum (Blue giant hyssop)
Cardamine concatenata (Crow’s toes, pepper root)
Gillenia stipulata (Indian physic)
Gnaphalium obtusifolium (Rabbit tobacco)