Helianthus ambiguus (Torr. & A.Gray) Britton accepted as Helianthus x_ambiguus (Torr. & A.Gray) Britton (original description)
Helianthus divariserratus R.W.Long (original description)
Helianthus filiformis (Small) R.W.Long (original description)
Helianthus grosseserratus subsp. maximus R.W.Long accepted as Helianthus grosseserratus M.Martens (original description)
Helianthus intermedius R.W.Long (original description)
Helianthus nuttallii subsp. coloradensis (Cockerell) R.W.Long accepted as Helianthus nuttallii subsp. nuttallii Torr. & A.Gray (original description)
Helianthus Xkellermanii (Britton) R.W.Long (original description)
Helianthus xluxurians (E.Watson) R.W.Long (original description)