64 



J. P. PUGH 



and D. filix-mas may also be formed where these plants occur in close association. 

 D. filix-mas is always the female and D. horreri the male parent since fertile spermatozoids 

 of D. horreri are formed but no ova ; such hybrid plants are being investigated. 



U 10 8 6 4 2 0 2 4 



10 8 6LongitudeWest 4of Greemvidi 2 OLoMoitudeFast 2ofGreeiiuic!i 



Fig. 4. Distribution of Dryopteris horreri in the British Isles. 



It is evident that much more work on this species is required but, as was mentioned 

 in the introduction, this is only a general account and from this it can be seen that 

 D, horreri is distributed throughout the British Isles, and that some important facts 

 may ensue from a study of the polyploid races. 



