100 INTRODUCTION TO BOTANY 
If the terminal bud of the spur contains leaves as well as 
flowers, a leaf bud is likely to grow in the axil of one of the 
leaves and thus provide for the growth 
of the spur during another year. This 
process may go on for a good many years. 
Evidently, when the spur produces a 
terminal bud containing flowers, it cannot 
Fic. 85. A lengthwise 
section of bud of thorn 
tree (Crategus) 
br, brown outer bud 
scales; 0, pale bud scale ; 
é, innermost rudimentary 
leaves; g, growing point 
at apex of twig, consisting 
of cells in a condition to 
sub-divide and multiply 
rapidly at the beginning 
of the growing season. 
Somewhat magnified 
grow straight ahead 
but must turn aside 
somewhat. <A. lit- 
tle study of the 
age of fruit spurs, 
made by cutting 
across them and 
counting the rings 
of growth, shows 
that they increase 
in length very 
slowly. This must 
be the case, since 
much of the plant 
food used by the 
spur is expended 
in producing the 
flowers and fruit. 
The flower scars 
on an old fruit spur are not all alike, 
some being much larger than others. 
This is because the smaller ones mark the 
places where flowers were borne but no 
full-grown fruit was matured, while the 
ones that bore successful fruit are larger 
and more sharply defined. 
What would be the effect on the 
growth of a young tree if all the fruit spurs or buds that 
produce them were pruned away year after year? 
yy 
RM 
\ 
\\ 
cad! 
Fie. 86. Twig of cotton- 
wood with buds in winter 
condition 
b.se, bud-seale scars. Two 
thirds natural size 
