THE FERNS AND THEIR ALLIES 5 



of leaflets. These leaflets are properly referred 

 to as pinnae. When the leaflets are subdivided 

 the divisions are spoken of as pinnules. These 

 pinnules may be deeply lobed, and when this 

 is the case each lobe is called a segment. In 

 very large fronds the pinnules are again divided ; 

 the frond is then said to be tri-pinnate. Some- 

 times towards the top of the pinnae or the frond 

 the divisions become less pronounced ; this 

 character is designated pinnatifid. It should be 

 noticed that the lower portion of the stalk, on 

 which there are no pinnae, is called a stipes. 

 Of course in some cases, as with the Hartstongue, 

 the leaf is quite undivided, without even any 

 very pronounced indentations on the margin. 



The unrolling of the Fern frond is a very 

 beautiful process. Where the leaf is not 

 divided in any way the process of expanding 

 resembles the uncoiling of a watch-spring. 

 Even where there are divisions the unrolling 

 goes forward in the same manner with each 

 subdivision, even down to the lobes. This 

 particular mode of unfolding is called circinate. 

 The texture of the leaves of Ferns is mostly thin 

 and delicate, so that apart from some exceptions 

 the foliage is not able to withstand the action of 

 dry air. A notable feature with a large number 

 of Ferns is the length of time which the leaves 

 take to develop. The fronds of the Male Fern, 

 for instance, start in the bud at least two years 

 before they actually unfold. An examination 

 will show that the roots of the Male Fern spring 

 from the frond bases. It will be found that 

 the position of the roots is the same in all 

 Ferns. 



With all Ferns the production of spores is 

 confined to the leaves. In many instances there 

 is no distinction between the fertile and the 



