Hops (Humulus Lupulus) are the tallest herbaceous creeper in our flora that can live for more than 20 years. It overwinters using a rhizome from which new stems grow each spring. It belongs to the hemp family. The female and male flowers occur on different plants (bisexual plant) and use the wind for pollination. It is only the unfertilized hop cones of the female hop plant that are used as raw material in the preparation of beer. These contain a yellow powder (hop flour) or lupulin that gives beer a bitter taste and also serves as a natural preservative.