Helianthus rigidus subsp. subrhomboideus (Rybderg) Heiser
Helianthus rigidus subsp. subrhomboideus (Rybderg) Heiser is a synonym sensu FNA Ed. Comm., 2006c of:
Helianthus pauciflorus subsp. subrhomboideus (Rydberg) O. Spring & E.E. Schilling, an accepted subspecies name sensu FNA Ed. Comm., 2006c.