POLYSTICHUM. 
89 
Polystichum Lonchitis, Both. 
The Alpine Shield Fern, or Holly Fern. 
(Plate IV. fig. 2.) 
This Holly Fern is a rigid and prickly-looking species; 
whence comes one of its English names. It has a scaly 
tufted stem, from the crown terminating which the young 
fronds are produced early in each spring. The fronds 
remain fresh and vigorous until after those of the suc¬ 
ceeding year are developed; so that the species is truly 
evergreen in its habit of growth. The size of the fronds 
is very variable ; sometimes they are not more than six 
inches long, and cultivated plants do not often much 
exceed this stature. In damp and but slightly elevated 
situations it becomes more luxuriant, the fronds sometimes 
attaining a foot and a half in length, and then having a 
vigour and robustness of aspect never acquired, as far as 
we know, in cultivation, at least in England. The climate 
of Ireland seems more congenial to it. The fronds are 
once pinnate, and narrow in outline, their figure being 
linear-lanceolate. The pinnse are short, crowded, and 
between sickle-shaped and crescent-shaped, the upper side 
at the base having an ear-shaped projection, called an 
