THE CYTOGENETICS OF CAREX FLAVA AND ITS ALLIES 135 



Table 3 



Artificial hybrids in C. flava aggregate 



No. of % Pollen Fertility 





Feincile PdTent 



h/Iale Parent 





o/" hybrid 



1. 



C. flava. 



X demissa 









Roudsea, Lanes. 



Loch Tummel, Perth. 



A ' 



on 



Z. 



C flava 



X lepidocarpa subsp. scotica 









Roudsea, Lanes. 



Cannich, Inverness. 



1 





-i 

 J. 



C lepidocaTpa 



A _y lava 









Tiefencastel, Switzerland. 



Preda, Switzerland. 



T 





A 



C. detnissa 



y\ jiaua 









a . France 



Roudsea, Lanes. 



-1 

 1 







b. Bredon, Leics. 



Roudsea, Lanes. 



n 





e; 

 O. 



C defnissa 



X lepidocarpa 









a. Shapwick, Somerset. 



Teesdale, Durham. 



c 

 J 



ZD 





b. France 



Wicken, Cambs. 









n \\/i]A TKmor T-i'oIl \\/i>ci-mr\r]ar-\A 

 C W llU UUdl 1 ell, W cbLlllUl IdllU 



WlLLcIlllg, i\OI LllallLb. 







A 













d. OLl llico iV±u*Jl , X-^cl uy olill C 



X vii^icocy. 



2 



29 





b . France . 



Hokatorp, Sweden. 



1 



J. 







C Ollcljp WlV^Jk, OUllicloCL. 



X viigicocy. 



5 









XVJ.WlXC^Ct, XlClCtJllvl. 







7 



C deTTiissa 



X scandinavica 



o 







OLl lllco 1V±\JIJ1 , JL^Cl Uyollllo. 



OWcLicll. 







Q 



o. 



C detnissa 



X mairii 









XJIciJvJll, JL^ClCo. 



i-^UlllUlClcio, Opdlll. 



o 







\^ , ot^lUt/lilti 



A Ic^LHUCCll pel 





94- 





Hokatorp, Sweden. 



Pvrpnpfx; 







10. 



C. mairii 



X lepidocarpa subsp. lepidocarpa 



1 







a. Pyrenees. 



Gordale, Yorks. 









C. mairii 



X lepidocarpa subsp. scotica 



2 







b. Pyrenees. 



Cannich, Inverness. 







11. 



C. mairii 



X serotina 









Pyrenees. 



Fulbourn, Cambs. 



2 





12. 



C. extensa 



X serotina 









Anglesey. 



Sweden. 



1 





13. 



C. hostiana 



X lepidocarpa 









Teesdale. 



Pyrenees. 



2 





C. flava is the relict and primitive member, with the lowest chromosome number, specialised 

 ecological requirements and relict distribution (Davies, 1953 d). The development of 

 the other ecospecies from C. flava has been accompanied by an increase in chromosome 

 numbers, a greater variation within the species and an ability to grow in a wider range 

 of plant communities. Thus C. lepidocarpa, with four more chromosomes, is more abund- 

 ant, adaptable and probably of more recent origin, although not so recent as the very 

 widespread and variable C. demissa with a capacity to flourish under various ecological 

 conditions. Lastly, C. serotina, with the same chromosome number as C. demissa, yet 

 requiring more specialised conditions, seems to be a more primitive and possibly a reduced 

 form, which needs the low sparse vegetation of an open habitat with little competition. 



It seems likely that this species, with the widest geographical distribution (Davies, 

 1953 d) of the group, spread rapidly during and after the last glaciation, recolonising the 

 open habitats produced by the retreating ice. Within recent times, owing to its specialised 

 requirements, this species has become confined to scattered and local areas ; probably the 

 presence of different forms which are not true ecotypes (as these differences do not seem 



