Helianthus laetiflorus var. subrhomboideus Helianthus rigidus subsp. subrhomboideus Helianthus laetiflorus var. subrhomboideus Helianthus rigidus subsp. laetiflorus Helianthus pauciflorus var. subrhomboideus Helianthus subrhomboideus Helianthus rigidus var. subrhomboideus
World Flora Online, http://www.worldfloraonline.org/, accessed June 20, 2024