The hop (Humulus lupulus L.) is a dioecious plant of the family Cannab(in)aceae, to which hemp (Cannabis sativa L.) also belongs. Only the hop cones of the female hop plant are used as essential raw material for beer. Female hop cones contain lupulin powder, rich in compounds that give beer a bitter taste whilst also acting as natural preservatives.
The hop is a sensitive plant and does not flourish everywhere. Hops have particular requirements regarding intensity and wavelength distribution of sunlight, and commercial hop cultivation is limited to areas between the 35th and the 55th parallels. The main hop-growing regions in the world are Hallertau (Bavaria), Yakima (Washington), Kent (UK) and Bohemia (Czech Republic) in the Northern Hemisphere and Australia and New Zealand in the Southern Hemisphere. In total, approximately 80 000 tons of hops are harvested from some 135 850 acres. There are about 40 different varieties (cultivars) of Humulus lupulus from which the brewer can choose, according to the style of beer he wishes to brew.