20 
BULLETIN" 925, U. S. DEPARTMENT OF AGRICULTURE. 
strated in figure 8, which shows frequency distributions of the three 
types of plants for the length of the longest internode. The longest 
internode, disregarding the very uppermost, which is sometimes diffi- 
cult to differentiate from the rachis of the tassel, is found almost 
always well below the ear, and hence below the area affected in the 
adherent plants. 
If the adherent variation is considered as being due to a single 
factor, completely coupled or linked with normal stature, then the 
adherent plants should be 25 per cent of the total, while the observed 
percentage is 19±1.85. While this deviation seems large, the nature 
of the variation is such that many of the plants must be eliminated 
in the seedling stage and doubtless escape notice. The percentage 
of adherent plants necessitates the assumption that this variation is 
recessive to the normal condition, and if the above hypothesis of 
perfect linkage with normal stature is correct, self-pollinated ad- 
herent plants 
should produce 
nothing but ad- 
herent plants of 
normal stature. 
The F x of a bra- 
chytic adherent 
cross should be 
normal with re- 
spect to both characters, and in the second generation there should 
be three classes of plants in the proportion of one normal in stature 
and adherent, two normal in stature and nonadherent, and one 
brachytic and nonadherent. The Boone plant which was crossed 
with brachytic must have been heterozygous for adherence, or other- 
wise it would have exhibited this character. Therefore, the prog- 
enies of one-half of the F x plants should have 25 per cent of the 
plants adherent. As yet only three progenies have been grown and 
two have exhibited the variation, but 30 additional hand-pollinated 
ears remain to be tested. 
I 
I- 
I 
/l/O/fs 
W?L 
lat 
YfCHri 
7&~— 
/%?/i 
EJ?£N1 
6 
IO /2 /+ /6 18 20 22 24- CM 
Fig. 8. — Frequency distribution of the length of the longest in- 
ternode on brachytic, adherent, and normal plants from the 
second generation of brachytic X Boone. 
EARS ENDING IN STAMINATE SPIKES. 
The staminate spike variation was found not only in the Boone- 
brachytic hybrid but also in some of the other brachytic-normal 
hybrids. The ears in this variation terminate in single spikes bear- 
ing several rows of paired staminate spikelets. The number of rows 
of these staminate spikelets, in the cases where they can be deter- 
mined with reasonable accuracy, is usually less than the number of 
rows of seeds upon the ear. 
The character is extremely variable in expression, especially in the 
second generation of the Boone-brachytic hybrid. In this hybrid, 
