This consensus document addresses the biology of the potato (Solanum tuberosum subsp. tuberosum). It contains general information on the taxonomy, morphology, and centre of diversity of the species which can be of importance during a risk assessment (for example, information on reproductive biology, the possibility of crosses, and ecology). In regard to intra- and interspecific crosses, emphasis has been given to the conditions which make a cross possible rather than listing all successful crosses. Such a list would be very long and subject to frequent changes. Only hybridisation events not requiring human intervention are considered.