21 



INCONSTANT FERNS. 



Although Ferns which are inconstant, that is, which do 

 not retain their varietal character, must occupy a back seat 

 in collections of the elite, they form a very interesting 

 study from the biological point of view, and in some cases 

 this defect is so far overborne by associated characters, 

 that they cannot be ignored. Thus we may mention that 

 otherwise beautiful fern Polypodhim vtilgave elegantisshmm 

 {covmihiense) as a prominent example. This variety bears 

 fronds of three distinct types, viz. normal, very slenderly 

 dissected, and more coarsely dissected, and these three 

 forms appear in the most wayward fashion, a single frond 

 shewing perhaps all three at once in varied degrees, a 

 single normal pinna appearing on a frond of the best de- 

 scription, or a finely dissected pinna on an otherwise quite 

 normal frond. This peculiarity is so inherent in the plant, 

 that although it has been raised by the thousand from its 

 spores, no one has succeeded in breeding out the fault, and 

 although improved plants, i.e. plants almost entirely formed 

 of the most finely dissected fronds {P. v. tvichomanoides), have 

 been obtained by root selection, even these revert more or 

 less to the normal and can only be kept true by elimi- 

 nating the normal or partly normal fronds as they appear. 

 Furthermore, it has been used as a factor in hybridizing 

 and crossing. Mr. Schneider succeeded in hybridizing it 

 with the large tender exotic Polypodium P. glaucnvi, produ- 

 cing huge plants of elegantissimuin type, and nearly hardy, 

 but still with precisely the same form of inconstancy ; 

 while Mr.Clapham successfully crossed it with a crested form, 

 with the curious result that its inconstancy produced, instead 

 of the three types of frond above described thus crested, 

 half a dozen types, some of the three bearing no crests. 



When we consider that all Ferns grow by development 

 of cells at the tips of their fronds and segments, it is seen 

 that in this case the mother or primary cells must be 

 constantly as it were altering their minds, so that a frond 



