206 CYTOGENETIC STUDIES IN DRYOPTERIS SPINULOSA : I 



Table 2 



Species or Hybrid 



Source 



2n 

 {Roots) 



n 



(bivalents 

 in brackets) 



Ploidy 



D. cristata (L.) A. Gray 



England 



c. 160 



(82) 



Tetraploid 



D. spinulosa (Mull.) Watt 



England 

 France 

 Germany 

 Sweden 



c. 160 



(82) 

 (82) 

 (82) 

 (82) 



Tetraploid 

 Tetraploid 

 Tetraploid 

 Tetraploid 



D. dilatata (Hoffin.) A. Gray 



England 



France 



Germany 



Ireland 



Shetlands 



Sweden 



c. 160 



(82) 

 (82) 

 (82) 

 (82) 

 (82) 

 (82) 



Tetraploid 

 Tetraploid 

 Tetraploid 

 Tetraploid 

 Tetraploid 

 Tetraploid 



" D. dilatata " 



Madeira 



Norway 



Scotland 



Sweden 



Switzerland 



82 



82 

 82 



(41) 



(41)* 



(41) 



(41) 



(41) 



Diploid 

 Diploid 

 Diploid 

 Diploid 

 Diploid 



" D. dilatata " 



Bavaria 





(38) + 47 



Triploid 



D. X uliginosa (Newm.) Druce 



Continent 



c. 160 



(39) - S6 



Tetraploid 



D. dilatata X spinulosa 



England 

 Ireland 



_ 



c. 160 



(33) -r 98 



(34) -f 96 

 



Tetraploid 

 Tetraploid 



D. dilatata (induced apogamy) 



England 



82 



82 



Diploid 



D. dilatata (4n) X " D. dilatata " (2n-Britain) 



S>Tithetic 



c. 120 



(39) -r 45 



Triploid 



D. dilatata (4n) X " D. dilatata " (2n-Nor\vay) 



Synthetic 



c. 120 



(39) 4- 45 



Triploid 



D. dilatata (4n) X " D. dilatata " (2n-Switzerland) 



Synthetic 



c. 120 



(39) - 45 



Triploid 



D. dilatata (4n) X " D. dilatata " (2n-Madeira) 



S>Tithetic 



c. 120 



(36) -T- 51 



Triploid 



" D. dilatata " (2n-Britain) X D. spinulosa 



Synthetic 



c. 120 



(3S) - 47 



Triploid 



" D. dilatata " (2n-Madeira) X D. spinulosa 



S>Tithetic 



c. 120 



(35) 4- 53 



Triploid 



* (Manton, 1950) 



The ancestral genome B is common to D. cristata and D. spinulosa, whilst C is common 

 to D. spinulosa and D. dilatata. That genome B cannot be common to all three species is 

 evident from hybrids known in N. America and those s\Tithesised between European 

 and American species of the complex (Walker, unpublished); this excludes the alternative 

 B -f D combination for D. dilatata as above. The combination C — A can also be 

 excluded since genome A must carry the factors responsible for simple pinnation in 

 D. cristata and the suggested genome D will be responsible for the erect rhizome habit 

 and scale colour in D. dilatata. 



