192 BRITISH FERNS 



Polystichum Angulare (The Soft Prickly Shield Fern) 



(Plate XXVIII) 



This beautiful evergreen species is closely allied to P. aculeatum, 

 the Hard Shield Fern, from which it differs in its softer texture, 

 more delicate cutting, and the possession of definitely stalked 



Fig. 216. P. angulare (pinna). 



pinnules (Fig. 216), instead of wedge-shaped, stalkless ones. Al- 

 though perfectly hardy, its natural habitats do not extend so far 

 north as do those of P. aculeatum, and it grows with the greater 

 luxuriance in our warmer western counties, and particularly in 

 Ireland, while in Scotland it has been recorded in but a few of the 

 lowland and western counties, the writer adding Perthshire to the 

 list by finding a solitary small plant in a glen near Aberfeldy in 

 association with a number of young P. aculeatums. Some botanists 

 consider it to be simply a form of P. aculeatum, but no British Fern- 

 grower can accept this verdict, since the two species may be found 

 growing side \)y side in the same hedge and yet preserving their 

 distinguishing characters intact. It is true that intermediate forms 

 are occasionally found, but to our mind it is far more reasonable 

 to impute these to accidental crosses, owing to the intermingling of 

 species so closely related, or to that remarkable faculty of variation 

 which this species has evinced, and as a result of which the best 

 authorities have sometimes differed as to which species particular 

 " sports " belonged. With these remarks we will now describe such 

 varieties as are best worthy of mention, ignoring a considerable 

 number which have figured in previous works, but which are now 

 only recognized as sub- varieties of little or no merit. 



Acrocladon (Fig. 217).— Found in Devon by Mr. Mapplebeck ; 

 a unique form in the species, fronds branch again and again, the 

 branches terminating in bunch crests. 



