BOTANICAL GAZETTE 



[FEBRUARY 



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

 tary qualities of the branching habit, and consequently the pollination 

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

 plants proved unsuccessful, however, and all my experience in breed- 

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

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



FIG. i. "Russian" sunflower (Helianthus annuus 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 individual of its kind, it must have been fertilized 

 by means of pollen from the unbranched individuals. Assuming 

 that this branching habit is a Mendelian character, several possible 

 assumptions would lead to different expectations regarding the off- 

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

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

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

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

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



