84 POLYPODIUM DRYOPTERIS. 



The Polypodium dryopteris is found most plentifully in wild 

 mountainous districts and damp woods. In Scotland and Wales 

 it is exceedingly abundant, as it is also in Northumberland, 

 Durham, Westmorland, Cumberland, Yorkshire, and Lanca- 

 shire. Other counties are Derbyshire, StaiFordshire, Shropshire, 

 Cheshire, (rare,) Herefordshire, Worcestershire, Gloucestershire, 

 and Somersetshire. In Ireland it does not appear to be found 

 except in the county of Antrim, being the rarest of the Irish 

 Ferns. 



* The researches of Johnston, Wilson, Finder, Westcott, New- 

 man, Lees, Bennett, Furchas, Westcombe, Withering, Moore, 

 etc., have given to the world a list of British habitats too 

 numerous to mention. 



Common as this species is, it appears to be less subject to 

 change its form than most other species. Formerly the P. 

 Rohertianum of Kunze, (the P. calcareum of J. Smith,) was looked 

 upon as a variety of the present species, and indeed in the 

 form of the frond it does very closely resemble it, yet there 

 are certain characters Avhich will be hereafter enumerated, so 

 widely different that the two plants must be considered distinct. 



Mr. Moore, in the "Nature-printed Ferns," and Mr. New- 

 man, in his "History of British Ferns," have given such full 

 and valuable information of the British Polypodiums, that the 

 subject may almost be said to be exhausted. 



The Oak Fern is veiy readily cultivated in the hardy Fernery, 

 either flourishing amongst rocks, or planted in light damp soil; 

 it is very rapid in its growth, and therefore requires a light 

 soil to enable the rhizoma to creep along in all directions. Care 

 should be taken that it be planted in a shady part of the 

 Fernery, as sunshine upon the fronds robs them of that vivid 

 green which is so marked a feature in this Fern. In an early 

 season the fronds appear in March, but more commonly it is 

 April before they expand; they soon become fertile, and on 

 the first return of cold weather in autumn disappear once more, 

 the P. dryopteris being a deciduous species. Mr. Newman, in 

 his "History of British Ferns," has well described the appear- 

 ance of the young fronds as three little balls placed on wires. 



The Oak Fern is very constant to the typical form, being 

 less liable to vary from seedling plants than most species. 



Fronds ternate, pentangular-deltoid, perfectly smooth, mem- 



