16 lIISTORy OF BRITISH PERNS. 



the earliest of them do not last till autumn ; in others they 

 continue until touched by frost, from -^vhich the more 

 robust of them shrink, even as the tender sorts do from 

 drouo-ht as ^-ell as frost. Others are much more durable, 

 and the plants, if in a moderately-sheltered situation, be- 

 come evero-reen. These latter should be most extensively 

 adopted for culture uhere ornamental effect is an object. 

 We shall point out these peculiarities as we describe the 

 different species. 



The fronds of Ferns consist of two parts — the leafy 

 portion, and the stalk, which latter is often called the 

 sl/'pes. The continuation of the stalk, in the form of a 

 rib extending through the leafy portion, and becoming 

 branched when the frond is divided, is called the rachis. 

 If the frond is compound, that is, divided, so that there 

 is another set of ribs besides the principal one, the latter 

 is called the primary rachis, and the former the secondary 

 rachis. Few of our native species are so highly compound 

 as to possess more than a secondary rachis. In practice, 

 when the outHne or division of the frond is mentioned, it 

 is generally the leafy portion only that is referred to, ex- 

 clusive of the stipes. 



The stipes is generally furnished more or less with mem- 



