SCOLOPENDRIUM HTBRIDUM, WOODSIA AND POLYSTICHUM ILLTRICUM 



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Triploid h^bric/ 



Fig. 162. Explanatory diagram to Fig. 161. x 2000. Pairs in black, 

 univalents in outline. One univalent has not been identified. 



SUMMARY 



Three non-British wild hybrid ferns have been described. 



(i) Scolopendrium hybridum Milde, endemic to some Adriatic islands, is shown to be a 

 tetraploid. One possible parent, the south European S. hemionitis Lag., Garcia & Clem., 

 is shown to be diploid as expected, but nothing is yet directly known about the relation- 

 ship. 



(2) Woodsia. Some Swedish hybrids between W. ilvensis (L.) R.Br, and W. alpina 

 (Bolton) S. F. Gray have been shown to be triploid and to have chromosome pairing of a 

 type which suggests that the diploid species, W. ilvensis, is part-parental to the tetraploid 

 W. alpina. 



(3) Two collections of Polystichum illyricum Hahne from Switzerland have been shown 

 to contain triploids which indicate by their chromosome pairing that P. Lonchitis (L.) 

 Roth is part-parental to P. aculeatum (L.) Roth. The other possible parent of P. aculeatum 

 is thought to be P. angulare (Kitaib.) Presl (P. setiferum (Forsk.) Woynar), and this is 

 confirmed by chromosome behaviour in triploid hybrids between these two species. The 

 synthesis of the tetraploid P. aculeatum from a hybrid between P. Lonchitis and P. angulare 

 is therefore awaited. 



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