THE SHIELD FERNS. 



37 



frost, quite through the autumn, and often far into winter. 

 The British species of Polystkhum are three in number, but 

 of one of them there are very many highly interesting varie- 

 ties ; for an account of which we must again refer to our 

 Handbook of British Ferns. 



The name Polystichum is compounded of two Greek words, 

 signifying many, and ordei'; and it is applied to these plants 

 in allusion to the numerous regular lines of sori, which are 

 seen distributed over the fronds. 



ALPINE SHIELD FERN, OR HOLLY PERN. 



This Fern bears the scientific name Folystichwn Lonchitis. 

 Synonymous with this, but less often used, are Polypodium 

 Lonchitis, and Aspidium Lonchitis. 



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 ter- 

 minating which, the young fronds are 

 produced early in each spring. The 

 fronds remain fresh and vigorous, until 

 after those of the succeeding 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 culti- 

 vation, at least in England. The cli- 

 mate of Ireland seems more congenial 

 to it. The fronds are narrow in out- 

 line, their figure being linear-lanceo- 

 late ; they are once pinnate, the pinnae 

 being short, crowded, and between 

 sickle-shaped and crescent-shaped, the 

 upper side at the base having an ear- 

 shaped projection, called an auricle, 

 the lower side being, as it were, cut away. The margin is 

 set with spinous teeth. The veins are twice branched, the 



Polystichum Lonchitit. 



