Limits in Hybridization 
25 
SUMMARY 
As a result of our efforts to determine the limits in hybridization of 
Yitis rotundifolia with related species and genera, we have come to 
conclusions which may he summarized as follows: 
1. Yitis rotundifolia will hybridize with Y. munsoniana and some 
species of Euvitis, namely: Y. vinifera, Y. bourquiniana, Y. labrusca, 
Y. cordifolia, and Y. aestivalis, also with the varieties Winch ell, Concord, 
and others. Other species will be reported on later as time and material 
w T ill permit. 
2. It is doubtful if Y. rotundifolia will hybridize with all species of 
Yitis. 
3. Our efforts so far indicate that Y. rotundifolia will not hybridize 
either way with Partlienocissus quinquefolia (Planch.), P. tricuspidata 
(Planch.) or Ampelopsis heterophylla (Sieb. and Zucc.) var. Elegans 
(Koch). 
4. Vitis rotundifolia will hybridize with its own F 3 hybrids with 
other species of Yitis. 
5. Yitis rotundifolia when used as the male parent will hybridize 
quite readily with some species of Euvitis, hut when used as the female 
parent it will hybridize only rarely. Some combinations seem more 
congenial for hybridization than do others. 
6. The results that are reported in this bulletin do not establish any 
limit, hut will indicate what may be expected in the hybridization of 
Y. rotundifolia with the mentioned related species and genera. 
