io8 



BOTANICAL GAZETTE 



[FEBRUARY 



two things, namely, the fact that MENDEL'S law was not discovered 

 by economic plant-breeders and gardeners long ago, and that in certain 

 quarters the notion prevails that Mendelian inheritance is a function 

 only of self -fertilizing or inbred strains. 



FIG. 3. Curves showing the extent of branching in three families of "Russian" 

 sunflower; the dotted line at left represents the offspring of two unbranched parents; 

 the dotted line at the center represents the offspring of two branched parents, one of 

 which must have been an extracted dominant; the unbroken line shows the condition 

 of a family from the mother of the pure unbranched family, but with pollination 

 unguarded; the dominance of branching produces a branched offspring in each case 

 that successful fertilization took place by means of pollen from a branched plant. 



The foregoing account of experiments on the inheritance of the 

 branching habit in Helianthus annuus may be recapitulated in the 

 form of a family tree thus : 



Branched (DR)X Unbranched (R) 



28 B (DR) 



54B(DD+DR + RR) 

 68 B DD + DR + RR) 



(656 DDorDR) ) 

 J i3B(DDorDR) \ 



2 U (RR) 

 2 U (RR) 



31 U (RR) 



6 (RR) 



More or less branched 



22 U (RR) 



