COMMON PRICKLY FERN. 



PoLYSTiCHUM ACULEATUM. — Roth, De CandoUe, Schott. 

 Polypodium aculeatum. — Linneus, Hudson, Lightfoot, Bolton. 

 Aspidium aculeatum^ angulare, and lohatum, — Smith, Hooker. 



LOCALITIES. 

 England. "^ 



^ot'Snd.[ Universally distributed. 

 Ireland, j 



The genus Polystichuin contains the most Protean of all our 

 ferns. In the Magazine of Natural History, (New Series, vol. ii. 

 p. 48,) I have endeavoured to prove that we possess but a single 

 species of this genus ; and the introduction of a second, in this 

 monograph, although accompanied by an expressed doubt, will 

 show that the views I then entertained have been somewhat modi- 

 fied, if not abandoned, by subsequent observation. This genus 

 was estabhshed by Roth, and has been adopted by De CandoUe 

 and Schott ; it contains but few species, and these are mostly 

 inhabitants of temperate climates. 



Polystichum aculeatum, the Polypodium aculeatum of Lin- 

 neus, may be considered one of our commonest ferns. I have 

 seen it more or less abundantly in every county I have visited, 

 whether in England, Wales, Scotland, or Ireland. It seems to 

 delight in the protection of man, its favourite habitat being our 

 hedgerows, and its luxuriance is greatly increased by cultivation, 

 or even by its vicinity to cultivated lands ; its occurrence on our 

 moors, commons, and mountains is comparatively rare, its 

 stature diminutive, and its appearance often unhealthy. 



The roots of Polystichum aculeatum are unusually long, 

 strong, and tough; its rhizoma thick, tufted, and extremely 

 chaffy. The young fronds make their appearance in April and 

 May, the apex being circinate, bent backwards, and remarkably 

 graceful in its appearance : the pinnae of the young frond are 

 also circinate (see the vignette at p. 42.) The fronds attain their 



