Limits in Hybridization 
7 
In the second conclusion, we see where Dr. Wylie successfully hy¬ 
bridized Yitis vinifera with pollen from Yitis rotundifolia. From the 
hybrid seeds he grew progeny which consisted of two types, namely: 
male (staminate) plants and imperfect hermaphrodite plants which 
bore no fruit. 
Although these hybrid vines are nowhere described, any doubt as to 
the authenticity of their hybrid nature is soon dispelled when we read 
that the imperfect hermaphroditic plants bear no fruit. This means 
that they were practically sterile. From our work with hybrids of this 
nature to be published in another bulletin, we have observed that this 
sterility is very pronounced and typical in the F 3 hybrids and such 
sterility should not occur if his seedlings were not true hybrids. 
Furthermore, in his last paragraph, Dr. Wylie clearly states that the 
blooming period of these hybrid vines is like that of the “Scuppernong” 
(meaning Y. rotundifolia) which is later than that of nearly every 
other species. With us Y. rotundifolia begins to bloom fully two weeks 
later than Y. vinifera, and some of the hybrids also bloom at a similarly 
late date. Unfortunately these Rotundifolia hybrid vines of Dr. Wylie 
were lost to horticulture during a period of misfortune that befell that 
great Grape Breeder. 
From this data, meagre as it is, the evidence is quite clear that Dr. 
Wylie must be recognized as having been the first to successfully hy¬ 
bridize Yitis vinifera with Yitis rotundifolia pollen. 
Dr. Wylie failed completely to hybridize Yitis rotundifolia with 
pollen from any species of Euvitis, their hybrids, and even from his 
own male (staminate) hybrid Rotundifolia vines. He also failed com¬ 
pletely to hybridize Y. labrusca, Y. aestivalis, Y. cordifilia or any other 
native species of Yitis or their hybrids with Y. vinifera, with pollen 
from Y. rotundifolia. It seems his conclusions were based on insuffi¬ 
cient experimental evidence because many such hybrids have since been 
produced. 
From the very nature of the sterility of the F 3 hybrids with species 
of Euvitis, and also from the fact that hermaphroditic varieties are 
frequently subject to self-fertilization in the bud, Beach* (1), M. J. 
Dorsey (2), Fledrick and Anthony (3), it seems rather doubtful whether 
Dr. Wylie actually produced the attenuated (prolific) hybrids as he 
states in his fourth and fifth conclusions. 
This resume practically covers the most important part of Dr. Wylie’s 
work in the hybridization of Yitis rotundifolia with related species and 
genera. He performed much work and attempted to establish and 
formulate limits beyond which hybridization cannot be effected, but fell 
far short of attaining that end. His conclusions are, therefore, subject 
to revision. 
* References to cited literature will be made by number. 
2 
