«Com insucesso da mamona Petrobras aposta no girassol[ligação inativa]» 🔗. Diário de Natal. Consultado em 20 de Agosto de 2008
botanicus.org
Gerard, John (1597). Herball, or Generall Historie of Plantes. London: John Norton. pp. 612–614. Consultado em 8 de agosto de 2012 Popular botany book in 17th century England
"Many people are under the misconception that the flower heads of the cultivated sunflower (Helianthus annuus) track the sun... Immature sunflower flower heads do exhibit solar tracking and on sunny days the buds will track the sun across the sky from east to west... However, as the flower bud matures and blossoms, the stem stiffens and the flower head becomes fixed facing the eastward direction." Hangarter, Roger P. «Solar tracking: sunflower plants». Plants-In-Motion website. Indiana University. Consultado em 22 de agosto de 2012
