MANY OR SPECIAL PURPOSES 345 



Hop leaves are cleft like those of the grape and 

 the hard maples. The inconspicuous flowers are 

 followed by clusters of pale green catkins or cones, 

 called "hops," that contrast beautifully with the 

 dark foliage. Only the fertile (female) plants 

 bear fruit in hops, the flower cluster of the sterile 

 (male) plants merely pollenating the fertile ones, 

 then fading, leaving the vine barren. 



Hops are a valuable crop to raise, since the 

 "burs" are used in the brewing of malt liquors. 

 Two pounds of dry hops are needed for each barrel 

 of beer. They give a pleasant bitter flavor to all 

 malt beverages, and keep them from turning sour. 



Young hop plantations are set with cuttings 

 from the root crowns of old plants. Various 

 systems of trellises are used to carry the vines up 

 where they get the sun to the best advantage, and 

 can be best let down for the picking of the crop. 

 The climbing goes on without help in fine weather, 

 the tendrils helped by the hooked hairs that 

 roughen the leaves. But gray weather dis- 

 courages the climbing, the shoots must be tied up 

 or they fall. They refuse to climb any slope of 

 less than 45 per cent., unless helped by being tied 

 at intervals. 



Four sterile plants to the acre are sufficient for 

 fertilization of the fruiting vines. When the burs 



