[Vol. 1 



388 ANNALS OF THE MISSOURI BOTANICAL GARDEN 



20 fig. 2 shows a rosette of this variety ia F3 (1911). One family 

 of 50 plants in 1910 contained 5 of this variety. Usually these 

 plants show partial variability, some flowers having broad 

 petals and others narrow and elHptical ones. Even the differ- 

 ent petals of the same flower may show these differences. 

 Flowers with elUptical petals are invariably smaller and are fre- 

 quently found on the side branches when those of the central 

 stem have normal petals. Hence this variation may be a matter 

 of strength in the plant. The variation, from petals which are 

 broad and truncate or emarginate to those which are narrow 

 and elliptical, or even almost cruciate, is continuous. Thus 

 on one plant in 1911, the dimensions of the petals in two flowers 

 were as follows : 



Flower 1. Petal (1) 31 mm. x 21 mm. 



Petal (2) 25 mm. x 17 mm. 



Petal (3) 20 mm. x 12 mm. 



Petal (4) 22 mm. x 13 mm. 



In this flower the petals are very small and very unequal in 

 size but all elHptical. 



Flower 2. Petal (1) 38 mm. x 39 mm. 



Petal (2) 37 mm. x 37 mm. 



Petal (3) 34 mm. x 36 mm. 



Petal (4) 35 mm. x 36 mm. 



In this flower the petals were nearly full size, nearly equal, and 

 scarcely elUptical. 



The inheritance of this condition is on a sliding scale, plants 

 with only broad petals giving some offspring with elliptical 

 petals, and plants with elliptical petals giving some offspring 

 having only broad petals, though in the latter case the plants 

 bearing elUptical petals are more numerous than in the former 

 case. Thus the F3 family from a normal plant contained 14 

 specimens having broad petals only and 15 having some eUipt- 

 ical petals ; while another F3 family of 44 plants derived from a 

 plant having elUptical petals contained only 5 plants having 

 exclusively broad petals. These pecuUarities of the petals are 

 probably to a large extent under the control of environmental 

 features such as temperature and water supply. 



The difference between broad and narrow leaves is much 

 sharper. Thus in my F4 cultures in 1912 certain famiUes contain 



