THE ALPINE POLYPODY. 89 



but it is believed to be extremely rare in that country. 

 In Ireland, no plants of this species have been found. 

 In Britain, Polypodium cakareum grows at various 

 heights up to twelve hundred feet above the sea-level. 



XXL THE ALPINE POLYPODY. 



Polypodium alpestre. 

 (Plate XIII., Fig. i, page 73.) 



LENGTH OF FROND. One foot to three feet and a 

 half. 



GENERAL DESCRIPTION. Roots fibrous, abundant. 

 Rootstock, a cormus, erect, short, tufted. Fronds broad, 

 lance-shaped, drawn out to a point at the apex, and 

 considerably narrowed towards the base ; bipinnate ; 

 pinnae alternate on the rachis, narrow, pointed, sym- 

 metrical, divided into pairs of oblong, somewhat blunt- 

 pointed, and deeply-indented pinnules. Stipes short, 

 with a few light-coloured scales scattered upon it. This 

 fern was for a long time confounded with the Lady 

 Fern, Athyrium filix-fcemina, but it was distinguished 

 from that species and included amongst the Polypodies 

 in 1841, having been discovered in that year by Mr. 

 Hewett C. Watson. Fructification distinct from Athy- 

 rium filix-fcemina, and consisting of round, non-indusiate 

 sori usually produced in two rows along each pinnule, a 

 sorus being placed ordinarily in those parts of the pin- 

 nules immediately contiguous to the bases of the notches 

 between the lobes. 



HABITATS. Shady rocks and streamsides ; often 

 covering considerable spaces of ground in mountainous 

 districts. 



