1924 j Collins: Inheritance in Crepis capillaris (L.) Wallr. 259 



A race obtained from Seattle, Washington (named "Seattle") 

 appears to be such a homozygous intermediate form. 



Races of Crepis capillaris also diflfer in number of lobes per leaf 

 and in length of leaf (Rau, 1923). The scalaris race shown in plate 

 52 has a large number of lobes. The two races differ, however, in 

 length of leaf. The leaves of the scalaris parent shown in plate 52 

 are shorter, and of the simplex parent larger, than the mean size 

 typical for each race. The Fj^ is usually larger than either parent. 

 The F, in the same figure shows the segregation for size which appears 

 to be due to multiple genes. 



The inheritance of pinnatifid and entire leaf forms in capillaris 

 conforms in general to the type of inheritance of corresponding forms 

 in a number of other plants. Rasmusen (1916) found in species 

 crosses in grapes that differences in leaf form behaved in a very 

 similar way. The F^ appeared to be intermediate between the shapes 

 of the parent leaves. In the Fo, a series was produced wdiich included 

 the grandparental forms, the F^ type and different grades of inter- 

 mediates. If the deeply toothed and intermediate toothed classes were 

 grouped together, a ratio of 3 toothed to 1 non-toothed resulted. 



ShuU (1918) found four different leaf forms of the shepherd's 

 purse to be caused by two pairs of factors. As in Crepis, the deeply 

 pinnatifid forms were dominant. The plants were also subject to 

 considerable fluctuating variation. Two races of IJrtica, one having 

 deeply serrated leaves, the other, leaves with entire edges, gave 

 serrated leaves in F^ and a ratio of 3 serrated to 1 entire leaf in 

 the F„ generation (Correns, 1912). In cotton, however, the deeply 

 palmately parted leaf form is not dominant when crossed with the 

 five-pointed upland type, but produces an intermediate type in F^ 

 with a ratio of 1:2:1 in the F2 generation (Shoemaker, 1909). 

 Kristofferson (1923) found that the difference in lobing of the leaves 

 of two species of Malva was brought about through a single genetic 

 factor, and resulted in a somewhat intermediate condition in F^ and 

 a 3 lobed to 1 non-lobed condition in the F,, although considerable 

 variation in the degree of lobing in the pinnatifid class was recognized. 

 Tedin (1923), on the other hand, found that pinnatifid and entire 

 leaved plants differed genetically by two factors. 



