UNITED STATES DEPARTMENT OF AGRICULTURE 
BULLETIN No. 925 
Contribution from the Bureau of Plant Industry 
WM. A. TAYLOR, Chief 
ji^H&JTU- 
Washington, D. C. 
PROFESSIONAL PAPER 
February 18, 1921 
A BRACHYTIC VARIATION IN MAIZE. 
By J. H. Kempton, Assistant in Crop Acclimatization. 
CONTENTS. 
Page, 
Definition of brachysm 1 
Review of the literature 2 
Origin and description of the varia- 
tion 2 
Inheritance of other brachytic varia- 
tions 6 
Morphological significance 8 
Associated changes 9 
Agricultural advantages 11 
Inheritance of brachysm in hybrids 
with commercial varieties 14 
Brachytic X Boone 14 
Teratological variations 19 
Ears ending in staminate spikes _ 20 
Brachytic X Hopi 23 
Conclusions 26 
Literature Cited 28 
DEFINITION OF BRACHYSM. 
Practically all the organs of maize are subject to profound modifi- 
cation, with heritable variations the rule rather than the exception. 
Many of these variations are undesirable abnormalities, and a knowl- 
edge of their origin and inheritance is of practical importance chiefly 
as an aid to their elimination. Among the many variations, how- 
ever, one has appeared which gives promise of becoming of agricul- 
tural value, since it possesses several highly desirable features ad- 
vantageous for dry-land and irrigated conditions. 
This variation consists of a shortening of the internodes without a 
corresponding reduction in their number or in the number and size 
of other organs. (PL I.) Variations of this nature are found in 
many agricultural plants, as, for example, the " bush " varieties of 
peas, beans, squashes, and tomatoes, and are popularly known as 
dwarfs. The distinction between this type of dwarfing and that in 
which many if not all of the organs have suffered a reduction in size 
has been pointed out by Cook (4 ),* who studied similar variations 
in cotton and suggested the term brachysm for that type which in- 
volves a shortening of the internodes only. 
1 Serial numbers in parentheses refer to " Literature cited 
16071—21 -1 
at the end of the bulletin. 
