IS 
BULLETIN 925. U. S. DEPARTMENT OF AGRICULTURE. 
in the number of rows on the upper ear. and in the length of the 
ear stalk. The brachytic plants, on the other hand, exceed the 
plants of normal stature in the number of branches in the tassel. 
the diameter of the culm, the total number of leaves, and the number 
of nodes that produce roots. The frequency distributions for the 
total number of nodes for the Boone, brachytic. and first and second 
generation hybrids are shown in figure 7. 
The reduced length of the branching axis of the tassel of the 
brachytic plants clearly indicates that brachysm includes the termi- 
nal inflorescence. Although the 
length of the rachis from which 
branches arise is reduced, the total 
number of branches is increased. 
This increase is comparable to the 
increase in the number of nodes on 
the culm, which is coincident with 
reduced stature. 
The abortion of the terminal in- 
florescence discussed on page 4 
did not appear in the progeny of 
the brachytic-Boone hybrid. As 
the evidence available thus far for 
this character indicates a Men- 
delian behavior, it would seem that 
the brachytic-Boone combinatioD 
will be free from this defect. 
It is an interesting fact that, 
although the longest internodes on 
brachytic plants are less than one- 
third the length of the longest 
internodes on normal plants, the 
length of the longest leaf sheath is 
not reduced on the brachytic plants. 
nor is the position of the sheath 
altered. 
There is a correlation of 0.434±0.047 between the length of the 
leaf sheath and the length of the internode on normal plants, indicat- 
ing a definite tendency for the sheaths to cover the internodes. Curi- 
ously enough, however, the longest leaf sheath does not inclose the 
longest internode. but on the contrary is produced, on the average, 
four internodes below the longest internode. That the correlation 
is no closer than 0.434 is not surprising, since the length of internodes 
on plants of normal stature is so largely determined by environ- 
mental conditions and may be altered at a comparatively late date, 
while the dimensions of the sheath are relativelv constant. 
an 
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20 
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17 19 21 23 2S 
NUMBER NODES 
27 
Fig. 7. — Frequency distribution for to- 
tal number of nodes in Boone, bra- 
chytic. Boone X brachytic Fi.and the 
normal and brachytic segregates in 
the F 2 of brachytic X Boone. 
