VARIATION IN THE IVIALE HOP, HUMULUS 

 LUPULUS L. 



By H. WORMALD, A.R.C.Sc, D.I.C, B.Sc. (Loud.). 

 {Research Department, South-Eastern Agricultural College, Wye.) 



The liop plant Humuhis lujndus L. is best known in Britain from 

 its cultivated forms grown for use in the brewing industry. Those 

 varieties which are grown on a commercial scale in this country all 

 conform to the general description of Humulus lupulus L. and the 

 presumption is that they are all variations (directly, or indirectly 

 through other varieties) from the female form of the original wild 

 hop. Since the j)lant is dioecious it follows that any one of these varieties 

 was in all probability derived primarily from one ? plant which arose 

 either as a mutation or as a hybrid and has subsei|ueutly been propagated 

 vegetatively by cuttings or "sets," i.e. the variety is represented by 

 a number of plants comprising a clone^ ; such a variety is not necessarily 

 provided with a corresponding male form possessing all the vegetative 

 characters of that particular $ variety. 



The varieties of the female hop are, at the present day, very numerous 

 but no attempt has hitherto been made to distinguish varieties of the 

 male plant, for, as Prof. Percival points out", "on account of their 

 being of no use to the grower, males have never been subject to special 

 selection and improvement." 



The value of the male hop to the practical hop-grower in this country 

 was, until a few years ago, a subject of much debate. Recent observa- 

 tions and experiments carried out at Wye College by Mr E. S. Salmon 



• The word "clone" was first used by Webber in 1903 and has been adopted by 

 Dr Jobs. Schmidt, Director of the C'arlsberg Laboratory, Copenhagen. In his recent 

 paper "On the Aroma of Hops" {Comptes-rendus dcs travaux du Laboraloire de Carlsherg, 

 lime Vol. 1915) Dr Schmidt, in discussing the use of the word "clone," writes {loc. cit. 

 footnote, p. 153): "I would suggest that the word be adopted into the terminology 

 relatmg to hops, where such a term is actually needed. A hop-clone would thus be all 

 those plants derived from the same seedling by vegetative j^ropagation, a clone-plant 

 being any single plant belonging to the clone." 



' Agricultural Botany, 4th Ed. 1910, p. 345. 



