90 WHERE TO FIND FERNS. 



WHERE FOUND. Only in Scotland, in the counties of 

 Aberdeen, Argyle, Banff, Forfar, Inverness, Perth, and 

 Sutherland, occurring at elevations reaching from twelve 

 hundred to three thousand six hundred feet above the 

 sea-level, in company with, and in similar positions to, 

 Athyrium filix-famina until the highest range of that 

 species is reached, when Polypodhtm alpestre occurs 

 alone in the higher elevations. 



XXII. THE HARD PRICKLY SHIELD FERN. 



Polystichum aculeatmn. 

 (Plate XII., Fig. x, page 71.) 



LENGTH OF FROND. One to four feet. 



GENERAL DESCRIPTION. Roots long, fibrous, tough, 

 abundant. Rootstock, a large, tufted cormus, the crown 

 of which is raised above the ground. Fronds lance- 

 shaped, leathery in texture, dark green, produced in a 

 circle around the crown, which, with the short stipes, is 

 thickly covered with rust-coloured or reddish-brown 

 scales that are usually thickly scattered upon the rachis 

 and also upon the secondary rachides. Leafy part of 

 frond bipinnate ; pinnae alternate, lance-shaped, divided 

 into alternate, wing-shaped, serrated, and bristly pin- 

 nules, attached by their bases, more or less narrowed, to 

 the secondary rachides or midstems of the pinnae. The 

 pinnules, separate and distinct from each other at the 

 inner ends of the pinnae, are decurrent or merged into 

 each other at their bases, towards and at the apices of 

 the pinnae. The upper pinnule on each pinna situated 

 next the principal rachis is larger than any of the others 

 on the same pinna, and its apex sometimes overlaps the 



