13 



British Fern Varieties. 



By F, W. Thorrington. — Read Septe»iber llth, 1919. 



A glance through the latest edition of Hayward's " Botanist's 

 Pocket Book " shews that within the limits of our Fern flora are 15 

 genera of rolypodiacea:, the order comprising the great mass of our 

 modern ferns, in a geologic sense. In addition to these there are 

 two genera of HynieiiophyUacete, the " filmy ferns," two of Ophin- 

 glossace(E, and one genus of the Osiinindacecr, leaving on one side the 

 question of the " fern allies," as having no relevance to this subject. 

 " Hay ward " has been especially quoted as being the oracle of the 

 " splitters," and therefore not likely to underestimate our resources, 

 and his estimate of the above divides it roughly into 43 species. 



A total of only 48 species, it is true, looks very poor in compari- 

 son with some of the tropical islands of similar area to ours ; where 

 we frequently find several hundreds of species represented. Strangely 

 enough, however, we find this paucity of species more than counter- 

 balanced by a varietal capacity that, so far, is beyond that of any 

 other part of the globe. In fact, it might almost be stated that a 

 thoroughly up-to-date collection of our varieties, including both 

 wild forms and the strains raised from them, would have nothing 

 to fear as regards beauty of form and texture from the massed 

 battalions of the whole of exotic ferns. 



The main types of variation may be enumerated thus : — (1) 

 " cresting," including all forms from merely " bifid " tips, through 

 " furcate," " digitate," " polydactylous," " multifurcate," and 

 " corymbiferous " ends to pinnae and frond tip, until the process 

 culminates in " grandiceps " with huge balls of cresting ; (2) dis- 

 section of fronds, commencing with variously cut and " incised " 

 pinnje, and passing through a series of "bipinnate," " tripinnate," 

 " divisilobe," " multilobe," "decomposite," etc., until we reach the 

 gems of the fern world in the " plumosums," where the division is 

 often such that the whole surface of the frond appears covered with 

 a mossy " pile " of hair-like segments. (3) In addition to these two 

 main groups there are a number of subsidiary variants, such as 

 " congesta," with dense, closely packed fronds ; branched forms ; 

 " tailed " fronds or pinnae; " revolvens," with the fronds almost 

 rolled into a tube ; " cornutum " and " truncatum," similar in 

 origin, but "horned" when the midrib projects beyond the square- 

 ended " truncatum " ; variegated and " proliferous " or " bulbiferous " 

 types. The two latter are frequently found conjoined with many 



