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. 



Fia. 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 



