THE POLYPODIES. 197 



broaden somewhat as they join the rachis. Occasionally 

 they are slightly serrate. It sometimes happens that 

 fronds of this species are mistaken by the novice for 

 those of the Christmas fern which are also pinnate, but 

 the latter may always be distinguished by the eared 

 pinnules. 



About the middle of June the bright yellow-brown 

 sori begin to appear. They are found on the backs of 

 ordinary fronds in a double row near the margins of the 

 pinnules and mostly in the upper two thirds of the frond. 

 They are round, very regular in arrangement and so 

 large as to be quite conspicuous,looking like little buttons. 

 Except the narrow-leaved chain fern, none of our species 

 produce sori so large. There is no indusium. 



Among its commgn names are adder's fern, golden 

 polypody, golden-locks, moss fern, stone fern, stone 

 brake and wall fern. Most of these are of obvious deri- 

 vation. It was once considered valuable as a pectoral 

 and, boiled with sugar, was a remedy for the whooping 

 cough. Little, if any, use is made of it at present. Ac- 

 cording to some authorities, this is the original oak fern 

 although Phegopteris Dryopteris now has the title, 



The polypody has numerous varieties but few of them 

 are worthy of special note. The most famous is the 

 Welsh polypody which has a frond much broader than 

 the normal with the pinnae cut nearly to the midrib 

 into narrow segments making a bipinnatifid frond. It 

 is called the variety Cambricum, and is supposed to be 

 always sterile. It was originally found in Wales and has 

 seldom been noted in this country but is likely to occur 

 in any locality where the type is common. The other 

 varieties reported are angustum with narrow serrate pin- 

 nules, rotundatum with short, round-ended pinnules and 



