Genus 1. POLYPODIUM. 



GEN. CHAR. Sori circular, naked. Margin of the frond not re- 

 flexed. 



One of the most extensive and diversified genera of the order, 

 chiefly distributed over the tropical countries of the Western hemi- 

 sphere. Of the four British species, three have been occasionally 

 referred to 'other genera, on account of the supposed presence of 

 an indusium, noticed by Roth, a celebrated German botanist, but 

 certainly not to be detected, in any stage of development, in those 

 specimens that have passed under my own observation, either wild 

 or cultivated, which latter I have diligently examined at every 

 period of their growth. 



The generic name is formed from 770X1)9, many, and TTO?S, foot, 

 in allusion to the form of the branched rhizoma in the most common 

 native species. 



POLYPODIUM VULGARE. Common Polypody. TAB. I. 



Fronds lanceolate, deeply pinnatifid; segments linear-lanceolate, 

 obtuse, indistinctly serrated, approximate. 



Polypodium vulgare, Linnaeus. Ctenopteris vulgaris, Newman, 

 Hist. Brit. Ferns, 41. 



Very frequent about the roots and moss-grown trunks of trees, 

 on rocks, shady hedge-banks, walls, and old thatched roofs. The 

 rhizoma branches in all directions, the branches, when it has grown 

 long undisturbed, crossing each other and forming a thick mat-like 

 substance : it is at first clothed with a cuticle densely covered with 

 yellowish -brown, membranaceous, lanceolate scales, which, falling 

 off, or becoming obliterated during the winter, leaves the surface 

 nearly smooth and of a yellowish hue. The young fronds begin to 

 appear 'in May, rapidly attaining the full size, which varies accord- 

 ing to situation from the length of five or six inches to that of 

 twelve or eighteen : where much exposed, and at a distance from 

 the ground, they have generally in maturity a drooping habit, and 

 even become almost pendent, but in sheltered localities often retain 

 their original erect position throughout. The rachis is smooth, 

 grooved on the upper face, and bare about half or one-third of its 

 length. 



The lateral veins of the segments are alternate, and each divides 

 into from three to five branches, of which the lowest, directed up- 

 wards, always terminates midway, while the others are continued 

 nearly to the margin; all of them in the barren segments being 



B 



