HERITABLE CHARACTERS OF MAIZE 
VI. ZIGZAG CULMS! 
WILLIAM H. EysTER 
New York State College of Agriculture, Ithaca, N. Y. 
“zigzag culm” andd escribed in 
this paper, was first noted by Dr. 
R. A. Emerson in a number of F, cul- 
tures of a cross between Tom Thumb 
pop corn and a Missouri dent corn. 
Some of the families in which zigzag 
culm was first found were breeding true 
for this peculiar type of stem so that it 
must have occurred in earlier genera- 
tions without being detected. At first 
it was thought probable that this is an- 
other example of a mutation having oc- 
curred in a pedigree culture but the 
fact that zigzag plants have been found 
in the progenies of two different Fe 
plants makes it much less likely. Dr. 
Emerson self-pollinated a number of 
plants and found that they breed true 
for the zigzag culm. He also found 
that when he crossed them with plants 
with normal culms the F, plants are 
apparently perfectly normal. Because 
of the many other problems that were 
demanding his attention Dr. Emerson 
asked the writer to investigate further 
the inheritance of this culm abnor- 
mality. 
(es plant abnormality known as 
DESCRIPTION OF ZIGZAG CULM 
In the early life of the plant it is not 
possible, at least so far as external ap- 
pearances go, to identify the individuals 
which are destined to have zigzag 
culms. The character first becomes 
apparent about the time the plant 
comes into tassel. The first indication 
is what seems to be a flattening and 
broadening of the culm in the ear shoot 
region. This apparent flattening is 
due to the pulling away of the leaf 
sheathes from the culm. Within a re- 
markably short time the character is 
fully expressed and the plants appear 
as shown in the accompanying illus- 
trations. 
In Figs. 8, 9, and 10 are shown zigzag 
plants. It will be seen that these 
plants are more or less dwarfed, with 
the culm in the ear shoot region strongly 
zigzag and consequently pulled out 
of the leaf sheathes. Fig. 8 shows an 
entire plant, while in Figs. 9 and 10 only 
a part of the plant is shown. As these 
photographs were all taken from the 
same positions it is evident that the 
first plant is more dwarfed than the 
other two plants. The amount of 
dwarfing depends upon the number of 
internodes affected and the degree of 
the modification. The leaves are ap- 
parently normal except that the sheaths 
are pushed apart so that they do not 
clasp the internodes as they do in nor- 
mal plants. A normal plant of the 
same pedigree culture is shown in Fig. 
11. 
In many zigzag plants the internodes 
affected are many times shorter than 
their leaf sheathes and often the sheath 
stands off at right angles to the inter- 
node, as shown in Figs.9and 10. The 
plant shown in Fig. 8 had a number of 
its internodes so much shortened that 
the long leaf sheathes overlapped to an 
unusual extent in the region affected. 
In Fig. 13 is shown the same plant with 
the leaves cut away so as to expose the 
stem. The leaves of the normal plant 
shown in Fig. 11 were likewise removed 
and the culm photographed as shown 
in Fig.12. The internodes of the zigzag 
plant are not only shortened but much 
thickened. Apparently there is more 
rapid growth on the side of the inter- 
node above the leaf attachment which 
causes the internode to arch away from 
the leaf sheath. As alternate inter- 
1Paper No. 84, Department of Plant Breeding, Cornell University, Ithaca, New York. 
Photographs by I. W. Fisher, Department of Plant Breeding, Cornell University, Ithaca, 
New York. 
349 
