264 University of California Publications in Agricultural Sciences [Vol. 2 



in Crepis. The appearance of purple anthoeyanin color depends upon 

 a certain amount of sunshine and exposure to light. Plants known 

 to be capable of producing the color will show it to only a small degree 

 if conditions for anthocj^anin development are adverse, while, on the 

 other hand, races in which it does not normally appear conspicuously 

 will produce it under conditions of sudden exposure to direct sun- 

 shine or sometimes as a result of mutilation caused by animals or 

 insects. The development of anthoeyanin is a matter of degree, for 

 the potentiality for its development is not entirely absent from any 

 race so far obtained. In the viridis race we have it in its lowest and 

 in the H6 race in its highest development. Crosses between high and 

 low anthoeyanin races (other than 19.e8 mentioned above) in general 

 produced F^ plants showing the darker anthoeyanin of the H6 race, 

 but in F, produced a series of forms showing a gradation in pigment 

 from one parent to the other. In most cases the parental types were 

 also duplicated. One such cross, H6 X viridis e33, gave an F^ more 

 nearly like the H6, but in F2 the types were distributed as follows: 

 9 of H6, 3 of viridis, and 3 distinctly between these two parental types. 

 The segregation of anthoeyanin has been observed in other cultures 

 (e26= 3 to 1), but has not, in general, given sufficiently regular 

 results to warrant the drawing of conclusions regarding its genetic 

 basis. The analysis can only proceed when facilities are available to 

 control more accurately the environmental factors which alter its 

 development. 



DWAKF II (dll) 

 Plate 48, figure 2 



This variation first appeared in culture 21.99, which was the 

 second selfed generation from achenes obtained from Lyons, France. 

 It is characterized by a very small rosette of slender semi-scalaris 

 leaves which are blotched with yellow and yellowish red coloration, 

 gi\ang them the appearance of being about half-dead. Due to their 

 peculiar appearance the first plants were thought to be suffering from 

 poor environment, although adjacent plants were healthy. The plants 

 when mature are very small (3-6 inches in height), the stems very 

 fine and spreading. In the first culture the dwarf effect appeared to 

 be recessive (5 dwarfs in 16 plants) and bred true in the next gene- 

 ration. Culture 22.159 from 21. 99?^^, a normal plant, contained 51 

 plants, 3 of which were dwarf II and 3 somewhat dwarfish but not 

 typical for dwarf II. This is approximately a 15 to 1 ratio, and 



