THE POLYPODIES. 25 



Genus 16. HYMENOPHYLLTJM, Smith. 



1. H. tunbridgense. Pinnae vertical ; involucres compressed, 



serrate. 



2. H. unilaterale. Pinnae deflexed; involucres inflated, 



entire. 



Genus 17. OSMUND A, Linnaeus. 

 1. 0. regalis. The only British species. 



Genus 18. BOTRYCHIUM, Linnceus. 

 1. B. Lunaria. The only British species. 



Genus 19. OPHIOGLOSSUM, Linnceus. 



1. 0. wdgatum. Fronds ovate. 



2. 0. lusitankum. Fronds very small, linear-lanceolate, 



obtuse, fleshy. 



CHAPTER IV. 



THE POLYPODIES. 



THE Polypodies are named POLYPODIUM by botanists. They 

 are known from all the other British Ferns, by their having 

 the spore-cases arranged in little round patches placed on 

 the back of the frond, these patches not being at any 

 stage of their development covered by the membranous film 

 called an indusium; hence they are said to be naked, or 

 non-indusiate. This family includes five distinct kinds, and 

 there are many variations of the common sort. In some of 

 the species the fronds continue green through the winter, so 

 that they are evergreen ; while in others they last but from 

 spring to autumn in each succeeding year. 



The technical name Polypodium given to this family is 

 derived from the Greek, and literally means many-footed. 

 This has been explained to apply to the branching of their 

 creeping stems, and also to the protuberances on them which, 

 in the earlier stages of development, have some supposed re- 

 semblance to the feelers of Polypes. 



COMMON POLYPODY. [Plate L] 



The name which this plant bears among botanists is Poly- 

 podium vulgare. It has also been called Ctenopteris vul- 

 garis. The Common Polypody grows with a creeping stem 

 nearly as thick as one's finger, and covered over with pale 

 brown chaffy taper-pointed scales. From the upper side of 

 this stem, or rhizome, spring the fronds, and from its lowei 



