A STUDY OF THE VARIATION IN SEEDLINGS 

 OF THE WILD HOP {HUMULUS LUPULUS L.). 



By E. S. SALMON and H. WORMALD. 



{Research Department, S.E. Agnc. College, Wye, Kent.) 



(With Plate XXV.) 



In 1913 it was decided to investigate whether seedlings of the wild 

 hop showed any resistance to the attack of the mildew Sphaerotheca 

 Humuli (DC.) Burr., and if so, whether this resistance was correlated 

 with any morphological character. 



It was necessary therefore to obtain seed of the wild hop. H. Lupuhis 

 is indigenous in Southern, Northern and Mid-Europe and in Northern 

 and Mid- Asia \ Hooker (Students' Flora) and Babington {Mamial of 

 British Botany) describe the plant as a true native in the South of 

 England. The so-called " wild hop," however, found growing commonly 

 in hedges in counties such as Kent and Sussex where commercial hop- 

 growing is practised,is either an "escape" and belongs to some commercial 

 cultivated variety, or possibly may be a " cross " between the wild hop 

 and some cultivated variety. Similarly in those countries on the Con- 

 tinent where hops are cultivated, e.g. Germany, France, Russia, etc., the 

 same uncertainty may exist as to the true status of a hop growing 

 apparently wild^ At the commencement of our investigations we be- 

 lieved it to be a fact that the hop had never been cultivated in Italy, 

 and we procured, through the courtesy of Prof. P. A. Saccardo, seed of 

 the wild hop, collected by him and labelled " Vittorio (Treviso), ad sepes, 

 omnino sponte, Oct. 1913." Subsequently a doubt arose in our minds as 

 to the certainty of this seed having originated solely from the wild plant. 



1 The wild hop of North America is, we consider, a distinct species, viz. H. Americanus 

 Nutt. (1)*. 



2 In an article by J. Schmidt entitled " The occurrence of the wild hop in Denmark " 

 (C. r. trav. Labor. Carlsberg, Vol. xi. 314 — 329 (1917)) the author states : By " wild " is 

 here understood ' ' not cultivated." The forms studied by Schmidt cannot be regarded 

 therefore as the undoubted offspring of the truly wild species. 



* These numbers refer to the bibliography given at p. 267. 



