EFFECT OF ENVIRONMENTAL CONDITIONS UPON THE 
NUMBER OF LEAVES AND THE CHARACTER OF 
THE INFLORESCENCE OF TOBACCO PLANTS^ 
H. A. Allard 
Introduction 
Among tobacco growers it is a matter of common observation that 
the number of commercial leaves produced by tobacco plants varies 
considerably from season to season. It is commonly believed that 
drought and other conditions unfavorable to growth not only produce 
smaller sized leaves but also reduce the number of leaves. Since in 
actual field practice any count of the number of leaves is only ap- 
proximately accurate, an investigation was made to determine the 
true number of leaves and the character of the inflorescence produced 
by tobacco plants under different conditions of environment. 
Since the inflorescence of the tobacco plant is determinate or 
centrifugal in its mode of flowering there is no further production of 
internodes with the appearance of the terminal flower bud. The 
terminal blossom is the first to appear, followed by other blossoms 
arising from the nearest or inmost buds of the branches representing 
the terminal whorl. The lowest lateral branch of the inflorescence of 
the main stem is popularly termed the first bald sucker from the fact 
that it is leafless or l^ears only rudimentary leaves. In well-developed 
plants the first bald sucker is readily distinguished from the secondary 
axillary branches below, and is sometimes used as a convenient point 
from which to begin a count of the number of leaves produced by the 
plant. 
In the following investigations a count was made of every leaf 
above the cotyledons. In order to do this conveniently the same 
leaf on each plant, counting from the cotyledons, was marked by 
puncturing the leaf one or two times with a heated needle. This 
treatment affords a quick and simple method of marking any particular 
leaf, and at the same time prevents the possibility of inoculating the 
plants with the mosaic disease. 
^ Published by permission of the Secretary of Agriculture. 
493 
