SO HISTORY OF BRITISH FERNS. 
Polypodium alpestre, Sprengel. 
The Alpine Polypody. (Plate XXI.) 
This Fern has so remarkably the aspect of the common 
Lady Fern (Athyrium Filix-feemina ), that although 
common on the Scottish mountains, it has been till very 
recently overlooked, the plants having been supposed to 
belong to that species. It would appear to be plentiful on 
the higher parts of the mountainous districts of the coun¬ 
ties of Perth, Forfar, and Aberdeen, accompanying the 
Lady Fern in its lower range, but ascending to a consider¬ 
ably higher elevation than that plant. The fronds appear 
in May, and perish early in autumn. 
The plants of this Fern have a short decumbent caudex, 
producing fronds in tufts from the crown. They are from 
six inches to three feet or more in height, broadly lance¬ 
shaped, and attached by comparatively short stipes, clothed 
with broadish-pointed membranous scales. They are 
bipinnate, or sometimes subtripinnate. The lower pinnae 
are gradually shorter, so that the outline is truly lanceo-* 
late. The pinnae are linear-lanceolate, taper-pointed, 
spreading at an obtuse angle with the rachis. The pin¬ 
nules have a slightly wavy midvein, from which alter- 
