Which genus of plants is within the Asteraceae family, Tithonia or Hymenocallis?
Hymenocallis Hymenocallis (US) or (UK) is a genus of American plants in the amaryllis family.
Helianthus nuttallii subsp. nuttallii H. nuttuallii subsp. nuttallii, also known by the common name Nuttall's sunflower is a subspecies of "Helianthus nuttallii" in the genus "Helianthus" in the family Asteraceae. It is considered by The Plant List to be a synonym for "H. nuttallii". However, The Jepson Manual argues that it is distinct from the species.