FERNS 179 



The common polypody is often to be seen grow- 

 ing on the branches of oaks, as well as on moist 

 banks or even on damp walls, and is green during 

 the winter but withers up in hot dry weather. 

 There are some beautiful sports of this fern ; for 

 example, the Welsh polypody (P. cambrica). Two 

 very favourite small ferns, the oak and the beech 

 ferns, come under the head of polypodies. 



Brake fern is the only British pteris, and it often 

 comes as a surprise that the ribbon ferns of our 

 greenhouses, which are called pteris by every 

 costermonger nowadays, should be so closely re- 

 lated to the common brake of the woodland; but 

 the essential points are the same, for in all ferns 

 the distinguishing feature of each group is to be 

 found in the arrangement and position of the spore 

 cases. In pteris the spores come under the rolled 

 back edges of the fruiting fronds, whether these 

 are ribbon-like or broken up into many small pin- 

 nules or divisions. 



Hart's tongues, which are, perhaps, the best- 

 known of all British ferns, and need no descrip- 

 tion, have on the contrary slanting bars of spore 

 cases across their fronds on the under side. Of 

 all ferns this seems to vary most, into forked and 

 crested and fluted forms, though none exceed in 

 beauty the long dark-green fronds of the ordinary 

 hart's tongue, as it may be seen growing on wet 

 rocks or on the moist hedgerow banks of a Devon- 

 shire lane. 



Under these few heads will be found most of 

 the ferns which can be cultivated with ease in the 

 open air. Among the more difficult may be 



