Question: What plant do flowers  used primarily as a flavoring and stability agent in beer that are grown on  long distance path of 108 mi in southeast England, from Haslemere in Surrey to Hamstreet in Kent?
Sentence (from "Greensand Way"): The trail was opened on 15 June 1980 and is jointly managed by Surrey and Kent Councils who fully updated it in 2012 (route, waymarking, online guide).
Relevant evidence: No