14 INTRODUCTION. 



carefully rolled up so as to occupy the minimum of space the 

 pinnules on the pinnae, and the pinnae towards the rachis, which 

 in turn had been rolled up from its tip until with the stipes it 

 had been coiled right down to the junction of the latter with the 

 rootstock. Of course, this is quite the opposite of what really 

 takes place, as the frond has been formed in its rolled-up 

 condition, and the gradual expansion of all its parts as the 

 stipes and rachis gradually straighten out is an interesting 

 sight. 



The packing of the incipient foliage of plants in their buds is 

 indicated by the botanical term Vernation, and as the rolling 

 up is the prevailing type among ferns they are often said to be 

 of Circinate Vernation. In the Adder's-tongue and the Moon- 

 wort, however, the vernation is straight that is, the incipient 

 frond is rolled or folded lengthwise from the edges to the 

 centre (Plate 7). 



In the following descriptive pages we have scarcely mentioned 

 the -varieties of the native species. Such abstinence is due to 

 a desire to render the subject as simple as possible. The 

 pursuit of varieties comes as a rule when one has become fully 

 acquainted with the typical forms of some natural group, and 

 the description and discussion of them may therefore be left to 

 more advanced works which may be consulted at home rather 

 than in the field. Since the propagation and hybridization of 

 such varieties have become the study of a Pteridological Society, 

 the lists of varieties, natural and controlled, have grown into 

 hundreds for some of the species ; but though such a study is 

 of some scientific interest, it is outside the domain of the field 

 naturalist. 



