312 University of California Publications in Agricultural Sciences [Vol. 2 



11. Biennis (N = 20) has chromosomes comparable in size to those 

 of capillaris, and there is some experimental evidence which indicates 

 that it is a polyploid from a five-pair species. 



12. It is well understood that these data are simply suggestive, 

 but it is hoped that they may be of some use in taxonomic and hybridiza- 

 tion studies on Crepis. The evidence, based on especially favorable 

 cytological material, shows that it is entirely unsafe to assume that 

 even closely related species which have the same chromosome numbers 

 are identical in chromosome individuality; or to assume polyploidy 

 unless the sizes of the chromosomes have been compared. 



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