THE GENUS DRTOPTERIS IN BRITAIN 



members of the old genus Dryopteris, and their separation, suggested first by Newman 

 in 1 85 1, into an independent genus Gymnocarpium is perhaps desirable. If this were 

 done their names should be G. Dryopteris (L.) Newman and G. Robertianum (Hoffm.) 



<* If % * • ^ 



Fig. 72. Meiosis in Gymnocarpium, permanent acetocarmine. x 1000. a. The 'Oak Fern' in Britain. 

 b. The 'Limestone Polypody' in Britain, not countable with certainty but not less than 80 or more 

 than 84 pairs, c. The Oak Fern from Storlien, Jamtland, Sweden, showing 80 pairs of chromosomes 

 with exceptional clarity. For explanatory diagram see Fig. 73. 



Newman, and it may be said in passing that such a procedure has been advocated on 

 morphological grounds by many recent writers, e.g. Ching, Christensen and Holttum. 

 Summing up the information for the British species of 'Dryopteris' it may be stated 

 that not one but probably at least four distinct genera are actually represented, some 

 of which, notably Dryopteris in the narrow sense and Thelypteris, seem to have come from 



85 



