32 



alike from the excess of cold and drying influence of the winds, 

 is the chief cause of their not flourishing generally under exposure 

 in this part of England ; added to which, is the frequent alterna- 

 tion of excessive wet, during those seasons when the vital energies 

 of the plants are dormant : the injurious results arising from both 

 of these circumstances may be obviated, in a degree, by covering the 

 plants individually with an inverted garden-pot or a hand-glass at 

 the period in question, exposing it only in mild and dry weather. 

 This is a plan by which I have often succeeded in preserving some 

 of the higher alpine species of flowering plants that are otherwise 

 incapable of cultivation in the vicinity of the metropolis, and it 

 was the protection afforded to the above-mentioned specimen of the 

 fern before us. 



In England, the distribution of P. Lonchitis may probably be 

 found to be less confined than has hitherto been supposed, Mr. 

 W. H. Hawker having discovered it in July of last year (1853) on 

 Swarth-fell, near Ulleswater, and this year in one or two other 

 stations in the Lake district. 



POLYSTICHUM ACULEATUM. Prickly Shield-Fern. TAB. XVI. 

 XVII. 



Fronds rigid, lanceolate or linear-lanceolate, bipinnate : pinnules 

 confluent, obliquely decurrent, or attached by the point of their 

 wedge-shaped base; the upper basal ones largest; all spinose- 

 serrate, more or less auricled at the base. 



Polystichum aculeatum, Roth. Babington. Moore. Newman. 

 Aspidium aculeatum, Swartz. Smith. Hooker and Arnott. 

 E. B. Polypodium, Linntws. 



Common on hedge-banks and on the borders of woods and 

 thickets throughout the kingdom, and occasionally met with in 

 more exposed situations on heaths and mountains. The rhizomt 

 is large and woody, increasing in length very slowly, so that even 

 in old plants it is very short in comparison to its bulk. The fronds 

 grow in a tuft, in young specimens spreading out horizontally, but 

 in older becoming nearly erect in maturity, and attaining the 

 height of two or three feet : during the early period of develop- 

 ment they are usually very limp in texture, and the newly un- 

 folded pinnae and circiuate apex are liable to hang down with their 

 own weight, as if drooping for want of nourishment, but as 

 growth advances they acquire the characteristic rigidity so remark- 

 able in the foliage of this beautiful genus. The general outline 

 varies greatly in different specimens, and even in fronds belonging 

 to the same plant, being in some instances almost linear, in others 

 even broadly lanceolate : the division too is equally diversified, and 



