Stevenage Outer Orbital Path (STOOP) is a long distance path orbiting the town of Stevenage in Hertfordshire.
 Established by North Herts Ramblers Group, it is 27.4 mi long and is split into several sections, accessible via a series of links from the town.
 The route passes through Graveley, Walkern, Beane Valley, Datchworth, Woolmer Green, Knebworth Park, St Ippolyts and Little Wymondley.
 It was launched on 20 September 2008.
The E2 European long distance path or E2 path is a 4850 km (3010-mile) series of long-distance footpaths that is intended to run from Galway in Ireland to France's Mediterranean coast and currently runs through Northern Ireland, Scotland, England, Belgium, Luxembourg and France, with an alternative midsection equally designated via the Netherlands and east coast of England.
 It is one of the network of European long-distance paths.
The Wey South Path is a Long Distance Path in Surrey and West Sussex, England.
 For part of its 32-mile route it follows the banks of the River Wey and of the Wey and Arun Canal.
The Greensand Way is a long distance path of 108 mi in southeast England, from Haslemere in Surrey to Hamstreet in Kent.
 It follows the Greensand Ridge along the Surrey Hills and Chart Hills.
 The route is mostly rural, passing through woods, and alongside fruit orchards and hop farms in Kent and links with the Stour Valley Walk near Pluckley in Kent.
 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).
Hops are the flowers (also called seed cones or strobiles) of the hop plant "Humulus lupulus."
 They are used primarily as a flavoring and stability agent in beer, to which they impart bitter, zesty, or citric flavours; though they are also used for various purposes in other beverages and herbal medicine.
 The hop plant is a vigorous, climbing, herbaceous perennial, usually trained to grow up strings in a field called a hopfield, hop garden (nomenclature in the South of England), or hop yard (in the West Country and U.S.) when grown commercially.
 Many different varieties of hops are grown by farmers around the world, with different types being used for particular styles of beer.
The Great Glen Way (Scottish Gaelic: Slighe a' Ghlinne Mhòir ) is a long distance path in Scotland.
 It follows the Great Glen, running from Fort William in the west to Inverness in the east, covering 79 miles (127 kilometres).
 It was opened in 2002 and is one of Scotland's four Long Distance Routes.
 The Great Glen Way is generally walked from west to east to follow the direction of the prevailing wind.
 It can be walked in 5–6 days, or cycled in 2–3 days.
The E1 European long distance path, or just E1 path, is one of the European long-distance paths designated by the European Ramblers' Association.
 It has a total length of some 4960 mi .
 It begins in Norway at Nordkapp, and crosses the Kattegat between Sweden and Denmark by ferry.
 It passes through Denmark, Germany, and Switzerland to finish at Scapoli, Italy.
 This path is planned to be extended southwards to Sicily, in Italy.
The Fen Rivers Way is a long distance footpath that spans a distance of 50 miles .
 The path runs between the City of Cambridge and the town of King's Lynn in West Norfolk.
 It follows the course of the River Cam and River Great Ouse across the fenland landscape into the Wash.
 It provides a small part of European Long Distance Path E2 which goes from Nice to Galway.
The E5 European long distance path or E5 path is one of the European long-distance paths from the French Atlantic coast in Brittany through Switzerland, Austria and Germany over the Alps to Verona in Italy.
 It is waymarked over the whole 3200 km (1988 mi) distance.
 The heaviest used section is the last part, which crosses Europe’s highest mountains from Lake Constance to Italy (600 km, around 30 days).
 Even this part does not require climbing experience.
The E9 European long distance path, E9 path or European Coastal Path (French: "Sentier Européen du Littoral") is one of the European long-distance paths, running for 5000 km from Cabo de São Vicente in Portugal to Narva-Jõesuu in Estonia.

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?
Answer: Humulus lupulus