136 The Journal 
always in very few of the flowers. 
Partial or entire sterility of such 
hybrids is the rule. The 1% fertility 
in the nineteen natural hybrids here 
reported, and especially the 5% fertility 
in hybrid No. 14, is believed to be un- 
usually high, 
THE FREQUENCY OF HYBRID OCCUR- 
RENCE 
It is interesting to note here that eight 
of the nineteen hybrids here described 
were found in the practically identical 
varieties of wheat, Fulcaster and Dietz; 
four others were found in selections 
from a hybrid wheat, Crimean x Spelt, 
and three others in the Purple Straw 
variety. In only three other varieties 
were such hybrids found, although sev- 
eral hundred other varieties and strains 
were growing on the farm No reason 
for this is known, It cannot be deter- 
mined from the location of the plots or 
time of blooming the previous year that 
greater facilities for crossing occurred 
in the case of varieties in which hybrids 
were found. The Purple Straw is one 
of the first wheat varieties to bloom, 
while the Fulcaster and Dietz are about 
average in blooming time. 
The season of 1917 at Arlington 
farm seemed to be uncommonly favor- 
able for cross pollination of cereal 
varieties. In addition to these wheat- 
rye hybrids a great many cross-pollina- 
tions occurred between different varie- 
ties of wheat growing in the cereal 
nursery, as was evidenced by the num- 
ber of such hybrids found in the 
nursery there in 1918. Dr. H. V. Har- 
lan, Agronomist in Charge of Barley 
Investigations, also reports the finding 
of a considerable number of F, barley 
hybrids in his 1918 Arlington nursery. 
These were especially noticeable in a 
plot of beardless barley. 
Of the nineteen natural wheat-rye 
hybrids described in this paper eighteen 
were from seed that was grown the 
previous year on Arlington farm, 
Hybrid No. 18 was from seed that had 
been produced at the Agricultural Ex- 
periment Station, Stillwater, Okla. A 
of Heredity 
head of the Malakoy variety was sent 
to the Office of Cereal Investigations in 
the fall of 1917, and seeds from it were 
sown in a 5-foot row. In this row 
hybrid No. 18, shown in Fig. 21 was 
found. 
As stated above, three natural wheat- 
rye hybrids were found in the cereal 
nursery of, the Virginia Experiment 
Station at Blacksburg, Va., in 1918. 
No data were obtained on these, Mr. F. 
K. Wolfe reporting that, on account of 
lodging, the hybrid plants could not be 
found at harvest time. 
Several natural wheat-rye hybrids 
have been found, as stated above, on 
the farm of the State College of Agri- 
culture, Athens, Ga. 
In my previous article (loc, cit.) I 
reported on a hybrid sent to me from 
Brush Creek, Tenn. 
Natural wheat-rye hybrids have 
occurred, then, in five different locali- 
ties of the United States. I examined 
a considerable number of wheat fields 
in which rye was mixed in New York 
State in 1918, and a few such fields in 
Kentucky, but did not find hybrids of 
wheat and rye. 
Summary.—Nineteen natural wheat- 
rye hybrids were found on Arlington 
farm in 1918, and three were found at 
the Virginia Agricultural Experiment 
Station. From a study of the plants 
and comparison with wheat and rye and 
with known hybrids between these 
species, it is evident that these hybrids 
are all of the first generation (F), 
They must have developed from seeds 
formed by the natural fertilization of 
wheat flowers with rye pollen. 
Forty seeds were produced by these 
plants, approximately 1% of the flow- 
ers setting seed. Vigorous plants of the 
second generation are being grown 
from a portion of this seed, - 
The natural hybridization of wheat 
and rye is now known to have. occurred 
in five different localities of the United 
States—in northern and southwestern 
Virginia, in Tennessee, in Georgia, and 
in Oklahoma. 
