| Vital in brewing malt liquors and popular as ornamentation, the American hop vine is a perennial climbing herb cultivated in the northern temperate zone. Female hop plants produce the conelike pendulous catkins seen here. The catkin, containing overlapping leaf bracts and fruit, is the portion of the plant used in brewing. A fine yellow powder called lupulin or hop flour covers the catkin and gives the hop its bitter flavor and aroma. |