Sex reversal in the Japanese hop* 
JouNn H. SCHAFFNER 
(WITH PLATE 2) 
After it became evident that abundant reversal of the sexual 
state takes place in Cannabis sativa L., when grown in the green- 
house during the short days of winter}, experiments were also 
made by the writer on Humulus japonicus Sieb. and Zucc., the 
Japanese hop. This hop is usually an annual, the vine growing 
from 10 to 30 feet long when planted in early May. It is a 
diecious plant much like the common hop, Humulus Lupulus 
L.,- but the carpellate catkins are not glandular. Both the 
inflorescence and the vegetative parts of the flowers show decided 
sexual dimorphism. The staminate inflorescence is a loose 
panicle and the staminate flower usually has three, four, or five 
distinct sepals with three, four, or five stamens and no vestige 
of a gynecium; while the carpellate inflorescence is an ament- 
like, large-bracted spike, and the carpellate flower has an entire 
sheath-like perianth surrounding the bicarpellate ovulary with 
no vestiges of stamens. 
In recent years, both species of hop have been studied by 
Tournoist and by Winge.§ Both of these authors mention the 
occurrence of intermediate or monecious individuals in Humulus. 
Winge apparently obtained normal pollen from a monecious 
plant but does not state whether this plant was to be considered 
as staminate or carpellate. It is quite evident that in the hop, 
as in the hemp, the plants are originally determined as carpellate 
or staminate and the intermediate condition arises thru’ sex 
reversal during vegetative growth. Tournois reports 10 chro- 
mosomes in the gametophytes of both H. Lupulus and H. 
*Papers from the Department of Botany, The Ohio State University, 
O. 135. Bee 
+ Schaffner, John H. Influence of environment on sexual expression in 
hemp. Bot. Gaz. 71: 197-219. 1921. : 
t Etudes sur la sexualité du huoblon. Ann. Sci. Nat. Bot., 19: 49-I9I. 
1914. 
§ The pollination and fertilization processes in Humulus lupulus L. and H. 
japonicus Sieb. et. Zucc. Compt. Rend. Trav. Carlsberg 11: I-44, 1914. 
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