Consensus Documents are intended to be a snapshot of current information on a specific host organism or trait, for use during regulatory assessments. They are being published on the biology of certain plant species, on selected traits that may be introduced into plant species, and on biosafety issues arising from certain general types of modifications made to plants. This consensus document addresses the biology of Beta vulgaris L. (sugar beet). It contains a general description as a crop plant, taxonomy, centre of origin/diversity, reproductive biology, crosses and weed characteristics. However, its ecology to specific geographic regions is not presented, since this may vary from one geographic region to another. For the intraspecific and interspecific crosses, emphasis has been placed on detailing potential hybridisation between the cultivated species and their close relatives. In this document, only hybridisation events not requiring human intervention are considered, rather than listing all successful crosses, which would be very long and subject to frequent changes.