This is a list of varieties of hop (Humulus lupulus). As there are male and female plants, the flowers (cones) of the female plant are fertilized by the pollen of the male flowers with the result that the female flowers form seeds. These seeds are eaten by birds and hence spread over vast distances. Hops, specifically their female plants, have been grown as a commercial crop for the brewing industry for many centuries in many countries. The first documented mention of a hop garden is in the will of Pepyn III. The first breeding of different hop varieties took place at Wye College in Kent, England by E. S. Salmon in 1919 when he bred the varieties "" and "". As of 2012, there are around 80 varieties in commercial use around the world, and considerably more in development/trials.