WHAT IS A FERNf 103 



manner that is to say, from the top of the frond 

 spirally downwards. In the simple fronds there is 

 one simple unrolling from the base outwards to the 

 extreme uppermost point of the frond. In the 

 compound species of the plant there is first of all 

 the primary unrolling, and that is followed when 

 completed by the lateral unrolling of the leaves on 

 the rachis, which lateral unrolling is followed by 

 perpendicular and lateral unrolling in alternation. 



