May 10,1924 
“Hairy Neck ” Wheat Segregates from Hybrids 
573 
tion. In his studies on the nuclear divisions of the pollen mother cells of the 
wheat-rye hybrid he found degenerative phenomena in the pollen mother cell and 
in the pollen. “The degenerating phenomena of the pollen cells are observed at 
every stage of their development, e. g., in synapsis, spireme, the first division, the 
second division, etc.” Jesenko (4) in studies of the pollen mother cell of the 
wheat-rye hybrid also found abnormalities which would seldom permit the 
formation of fertile pollen. These cells seldom divided into 4 parts, as is natural 
in wheat and rye, but frequently divided into 3, 5, 6, or even more different parts. 
Pollen grains are formed in the F t wheat-rye hybrid, but nearly all of them are 
shrunken and poorly developed, and lack the usual cell contents. A few are 
found now and then, however, that are better developed and that may be capable 
of growth. But anthers filled with such pollen have never been found, and, 
probably on account of the resulting lack of internal pressure, no anther has been 
observed to dehisce. Fx plants isolated or bagged have always been sterile. 
Pollinations made by artificially rupturing the anthers also have not been success¬ 
ful. Jesenko pollinated over 3,000 hybrid flowers with pollen forced out of the 
anthers but no flower set seed. The writers have made several hundred such 
pollinations with like result. 
The F x wheat-rye hybrid appears to be self-sterile, but seeds sometimes are 
set on such plants when open pollinated. In 1922, at the Arlington Experiment 
Farm, 11,791 wind-pollinated flowers of Fx wheat-rye hybrids growing in the 
wheat plats produced 6.5 seeds per thousand, and in 1923, under similar condi¬ 
tions, 4,772 hybrid flowers produced 6.7 seeds per thousand. The results for 
the two years agree so closely that it appears that heredity rather than environ¬ 
ment is the factor determining seed formation. Leighty and Hutcheson (7) 
found, in 1919, that of the wheat flowers emasculated and exposed in the field at 
Arlington, 83.3 per cent set seed, a high seed formation for wheat heads. This 
indicates that an abundance of wheat pollen was disseminated by the wind to 
effect fertilization of exposed stigmas. It is well known also that rye pollen is 
widely disseminated by the wind. The flowers of the wheat-rye hybrid open at 
an average date intermediate between the average for wheat and rye, and, as is 
usual with small grain plants when fertilization has not occurred, remain open 
for a week or longer. Since the natural wheat-rye hybrids at Arlington grew in 
close proximity to both wheat and rye plants, there is little doubt that all their 
flowers were pollinated at some time or other with wind-borne pollen of both 
wheat and rye. The flowers thus pollinated produced on the average about 6.6 
seeds per thousand. Jesenko (4) obtained 3 seeds per thousand pollinations 
when he backcrossed his F x wheat-rye hybrid with wheat pollen (and one seed 
from almost 5,000 pollinations with rye). The difference in results obtained by 
the writers and by Jesenko probably indicates the greater effectiveness of natural 
pollination, and is in line with the results usually obtained in artificial crosses of 
wheat. 
Although the Fx wheat-rye hybrid has produced no seed when bagged, but 
when open pollinated has shown 0.66 per cent of fertility, it cannot be definitely 
concluded that the female gamete is more fertile than the male. No cytological 
studies of the egg mother cell of the Fx wheat-rye hybrid have been made and 
nothing is known regarding the phenomena connected with development of the 
female gamete. Self-sterility, when a head is bagged, may be due to lack of 
development of sufficient pollen in the anther to cause dehiscence. Following 
artifical rupture of the anthers and self pollination, it may be due to the same 
causes that are responsible for the usually nearly complete self-sterility in rye 
itself. It is evident, however, that the stigmas of the Fx are brought into con¬ 
tact with viable pollen of wheat and rye more frequently than the pollen of the 
