Humulus lupulus Hop

A coarsely hairy, perennial climber which has sharply-toothed leaves, some with three lobes and somewhat Ivy-like in appearance. It is a member of the Hemp family (Cannabinaceae) and like other members of this family individual plants are either male or female (i.e. it is dioecius). The small, greenish-yellow male flowers are produced in a branched catkin and the female flowers are produced in rounded heads which enlarge to become the cone-shaped hops. It grows in open woodland and hedges and is widespread in much of southern Britain, including Wales. It is usually regarded as a native species but has long been cultivated for its hops which are used to flavour beer. Some populations are undoubtedly derived from cultivated stock (originally introduced from Flanders in the 16th Century) and it is now difficult to differentiate between native and alien populations in some parts of the country. It is rather local in its distribution in West Glamorgan with frequent occurrences in north Gower hedges and scattered occurences elsewhere but it is quite scarce in Neath Port Talbot where it occurs in some old hedges. It is probable that most plants in West Glamorgan are native. The flavour of hops comes from a number of compounds produced in the yellow lupulin glands inside the femle cones, which contain alpha-acids like humulone and a variety of hydrocarbons that make up most of the volatile oils that give woody, herbal or pine-like flavours.