X04 



BOTANICAL GAZETTE 



[FEBRUARY 



Not until late in the season was it decided to investigate the heredi- 

 tar^' qualities of the branching habit, and consequently the pollination 

 was not guarded. Attempts at getting self -fertilized seeds from other 

 plants proved unsuccessfulj howeveij and all my experience in breed- 

 ing the sunflowers during the past four years indicates that they are 

 entirely seK-sterile. From this it may be safely inferred that the 



Fig. I. — **Russian" sunSower {Helianthus annuiis var. hort.) showing two pure- 

 bred strains; unbranched on the left, branched on the right. 



branched individual (pedigree no. 04109) was cross-fertilized; and 

 as it was the only indi\-idual of its kind, it must have been fertilized 



means 01 pollen from the unbranched 



Assuming 



that this branching habit is a Mendelian character^ several possible 

 assumptions would lead to different expectations regarding the off- 

 sprmg of this cross : (a) If the unbranched habit were dominant over 

 the branched, all the offspring should be unbranched; (6) If the 

 branching habit were dominant, there would be two cases: (i) when 

 the teanched parent is a pure dominant, the offspring should be all 

 branched; and (2) when the branched parent is a heterozygote (DR), 



