A DROUGHT-RESISTING ADAPTATION IN SEEDLINGS 
OF HOPI MAIZE 
By G. N. Coixins, 
Botanist , Office of Acclimatization and Adaptation of Crop Plants, 
Bureau of Plant Industry 
INTRODUCTION 
A study of the maize grown by the Hopi, Zuni, and Navajo Indians of 
New Mexico and Arizona has brought to light an adaptive character that 
promises to be of economic importance in dry regions where germination 
is uncertain. 
These southwestern Indians have preserved from pre-Columbian times 
a type of maize able to produce fair crops in regions where the better 
known varieties of the East fail for lack of sufficient water. An impor¬ 
tant factor in the drought resistance of this type of com is its ability to 
force the growing shoot of the seedling to the surface of the soil when 
planted at a depth of a foot or more. At such depths less specialized 
varieties die before reaching the surface. 
The literature of corn contains reports of many experiments conducted 
to determine the proper depth of planting, but the results are confusing 
and contradictory. It has generally been realized that the optimum depth 
is influenced by differences in soil and climate, but that the proper depth 
might vary with different varieties seems not to have been appreciated. 
The experiments referred to later, as well as many unpublished data 
showing the varying behavior of types when planted at different depths, 
indicate that it is unsafe and unscientific to generalize with respect to 
cultural factors without taking type, varietal, and even individual differ¬ 
ences into account. 
MORPHOLOGY OF THE MAIZE SEEDLING 
To explain this drought-resistant character, it will be necessary to 
discuss briefly the different parts of a maize seedling. (See fig. i.) The 
primary root, or radicle, which is the first organ to emerge from the ger¬ 
minating seed, is soon followed by the shoot or plumule. Inclosing the 
shoot is the cotyledonary sheath, or coleoptyle, a tubular organ which 
is closed and pointed at the upper end. Between the base of the coleop¬ 
tyle and the seed the axis is somewhat elongated. With seeds germinated 
in the laboratory this elongation is so slight that it might easily be over¬ 
looked. Nevertheless, this small organ has not escaped the notice of mor¬ 
phologists, and its nature has been the subject of much discussion. It has 
Journal of Agricultural Research, 
Dept, of Agriculture, Washington, D. C. 
(293) 
Vol. I, No. 4 
Jan. 10, 1914 
0-8 
