SPECIES HYBRIDIZATION 



241 



sylvestris in all their characters. These latter plants are fertile .and in 

 succeeding generations give offspring which to all indications are pure 

 sylvestris individuals. Similarly when pollen of the N. tabacum parent 

 is used, the sesqui-hybrids are of a variety of forms, but all approximate 



FIG 104. Xicotiana tabacum "Cuba" (left) and its Fi hybrid with N. syloestris (right). 

 (After Goods peed and Clausen.) 



the N. tabacum parent in their characters and no one could determine by 

 studying them that they were only once removed from N. sylvestris. Those 

 which most closely approximated the N. tabacum parent in morphological 

 characters are also most fertile and give rise to fertile races which do not 

 differ significantly from the N. tabacum parent. 



16 



