There are four subspecies. Vipera berus berus has the greatest range and is the subspecies found in Britain.
Females are larger than the males.
Physical Appearance Adders are relatively short and robust with large heads and a rounded snout. Females are brown with dark red-brown markings. Their undersides are black. Distribution Adders are the most northerly distributed snake - they are the only species found inside the Arctic circle. They occur throughout Europe, with the exception of Ireland and the Mediterranean islands, and across Russia and Asia through to N. China.