Consensus documents contain information for use during the regulatory assessment of a particular product. In the area of crop biosafety, consensus documents are being published on the biology of certain crop species, on selected traits that may be introduced into crop species, and on biosafety issues arising from certain general types of modifications made to crops. This consensus document addresses the biology of Helianthus annuus (L.) (sunflower). Included are descriptions of the taxonomy of the genus Helianthus; the natural habitat and the origins of the cultivated sunflower; the botanical, physiological and agronomical characteristics of the cultivated sunflower; the possibilities for intraspecific crosses; and the potential interactions with other organisms (insect pests, pathogens, and animals).