Try to make your search as simple as possible:
Archangelica will find all items including that sequence of letters.
Search results for "Archangelica":
"Archangelica decurrens" - Angelica decurrens
"Archangelica gmelinii" - Angelica gmelinii
"Archangelica officinalis" - Angelica archangelica
"Archangelica songarica" - Angelica brevicaulis