12 COHESION. 
about. This is one of the most common of all mal- 
formations, and seems to affect certain plants more 
frequently than others. In its simplest-form it consists 
of a flat, ribbon-like expansion of the stem or branch ; 
cylindrical below, the branches gradually lose their 
pristine form, and assume the flattened condition. 

Fig. 4.—Fasciation in Asparagus. 
Very generally the surface is striated by the pro- 
minence of the woody fibres which, running’ parallel 
for a time, converge or diverge at the summit according 
to the shape of the branch. If the rate of growth be 
equal, or nearly so, on both sides, the stem retains its 
straight direction, but it more generally happens that 
the growth on one side is more rapid and more vigorous 
