38 BRITISH PERNS. 



branches extending to the margin without joining with 

 others. The clusters of sp_ ore-cases form a line parallel with 

 and on each side of the midrib, and are covered each by a 

 membranous circular scale, which is attached by a short 

 central stalk. 



This is a true rock-Fern, occurring on the bleak moun- 

 tains of Scotland and in the milder climate of Ireland, as 

 well as, rarely, in the north of England and Wales. 



The Holly Fern is very distinct, and, when vigorous and 

 healthy, not inelegant, but it is difficult of cultivation, and 

 is seldom seen thriving under artificial treatment. 



COMMON PRICKLY SHIELD FERN. 



This is Polystichum aculeatum, the Poly podium aculeatum 

 and Aspidium aculeatum of the older writers. 



Fia. 7. 



Polystichum aculeatum. 



The plant is almost evergreen in a sheltered situation, 

 and is one of those specie which are well suited by boldness 

 of character for the decoration of rocky scenery. It is a 

 jtout plant, having the fronds a couple of feet or more long, 

 and springing from a stout tufted stem or crown, whence 

 they grow up in a circle, about the month of April, and take 

 a somewhat erect position. They are lance-shaped in form 



