MORACEiE 265 



northern part of the continent of Europe and in Asia as far as 

 eastern Siberia and south to Persia; it also grows wild in 

 North America, across the continent westward to New 

 Mexico and British America. It requires a moist, cool ch- 

 mate to attain its best development. Oregon, California, 

 New York, and Washington are the leading States in the 

 commercial production of hops. 



Closely Related Species. — Humulus japonicus, the Japa- 

 nese hop, is grown as an ornamental plant. It is an annual ; 

 its pistillate inflorescence does not enlarge into a "hop." 

 Along streams from Wyoming to Utah, New Mexico and 

 Arizona, there is a hop (Humulus lupulus neomexicanus) 

 which is distinguished from the Linnaean species by its more 

 deeply divided leaves and more sharply acuminate bracts. 



Varieties. — There are a number of varieties of hops, based 

 upon length and color of vines, size, shape and color of hop, 

 shape of bracteoles and stipular bracts, aroma, lupulin con- 

 tent and time of ripening. In Cahfornia the chief variety is 

 Large Gray American. Common New York varieties are 

 Enghsh Cluster, Pompey, Humphrey Seedling and Canada. 



Composition. — The composition of the strobiles or hops is 

 of great importance, for they possess the valuable constitu- 

 ents of the plant, most of which reside in the lupulin glands. 

 There are four principal active ingredients in the "lupuUn," 

 as follows: 



1. Essential oil. 



2. Non-resinous bitter principle. 



3. Resins. 



4. Tannin. 



Hop oil is volatile and gives the hop its characteristic 

 aroma. The amount of essential oil in hops varies from 0.2 

 to 0.8 per cent. The non-resinous bitter principle of the hop 



