iia. 

ber of internodes between two successive 
THE STEM 105 
attachment of every leaf 3/8 of the way around the stem from 
the next in age (Fig. 100). In this case the point of attachment 
of a leaf is directly above that of the eighth below, and there 
are three turns in the spiral for every eight leaves. 
Divergence of alternate leaves. The proportion of the distance 
around the stem that a leaf is removed from the one next in age 
is called the divergence. When leaves 
are two-ranked (halfway around the 
stem from each other) the divergence 
is 1/2. We have just considered cases 
in which the divergence is 1/2, 1/3, 2/5, 
and 3/8. These figures, however, show 
other relations than the divergence. In 
the case of a divergence of 3/8 (Fig. 100) 
the denominator 8 shows the number of 
internodes between two successive leaves 
that are in the same vertical line on the 
stem, and also the number of vertical 
rows in which the leaves are arranged 
on the stem. The numerator 3 shows the 
number of turns of the spiral for every 
eight leaves. The same relation holds 
for all other divergences. In the case of 
2/5 the denominator 5 shows the num- 






leaves that are on the same vertical line 
and the number of rows in which the p44 100, Diagram Pe, 
leaves are arranged. The numerator 2 ing arrangement of eight- 
shows that there are two turns in the ranked leaves 
spiral for every five leaves. When the 
divergence is 1/3, every leaf is above the third below, the leaves 
are arranged in three rows, and there is one turn of the spiral 
for every three leaves. 
The greatest divergence that occurs with alternate leaves is 
1/2, and the smallest is 1/3. All other divergences are inter- 
mediate between these two. 
