ANTHOCYANINS AND GENETICS 191 



flower. It is difficult to define the limits of striping for, on the one hand, 

 among striped varieties we frequently find sectorial variations in which 

 colour is definitely and symmetrically confined to a half, a third, or 

 some other fraction of the flower. On the other hand, striping may 

 pass into spotting or blotching, and it i questionable whether spotted 

 and blotched flowers- should be placed in the same category, though 

 their genetical behaviour may be similar. Some of the genera and 

 species in which striping occurs are the following: 



Antirrhinum ma jus, Papaver, 



Cheiranthus Cheiri, Petunia, 



Dahlia variabilis, Primula sinensis, 



Dianthus Caryophyllus, Tagetes, 



D. barbatus, Tulipa, 



Mirabilis Jalapa, Zinnia elegans. 



As further examples of striping and sectorial variation, we may 

 add those mentioned by de Vries (565), i.e. Celosia variegata cristala 

 (inflorescence), Centaurea Cyanus, Clarkia pulchella, Convolvulus tricolor, 

 Cyclamen persicum, Delphinium Ajacis, D. Consolida, Geranium 

 pratense, Helichrysum bracteatum, Hesperis matronalis, Impatiens 

 Balsamina, Nemopliila insignis, Papaver nudicaule, Portulaca grandi- 

 flora and Verbena. 



Striping may be regarded as a variation under normal conditions 1 ; 

 there is, however, a kindred phenomenon called flaking which appears 

 in flowers, otherwise self-coloured, towards the end of the vegetative 

 season, or when the plant is in an unhealthy condition. Ex. Dahlia 

 (Hildebrand, 458, 466), Matthiola. 



Striping is apparently not a phenomenon which occurs in plants 

 in the wild state, and, according to the theory of Louis Vilmorin, as 

 expounded by de Vries (565), it only appears in coloured plants which 

 have already produced a white or yellow variety, that is a variety free 

 from anthocyanin pigment. It is certainly true that striping is most 

 usual in connection with anthocyanin; as a rule it is not shown by 

 soluble yellow pigments (Antirrhinum, Althaea), though in Papaver 

 nudicaule, according to de Vries (565), one finds a yellow variety with 

 dark orange stripes. In Mirabilis, also, yellow pigment may be found 

 striped upon a white ground. Flowers with yellow plastids rarely, 

 if ever, occur in the striped condition ; such yellow flowers may, however, 

 occasionally show light segments containing paler derivative plastid 



1 De Vries (565) notes, however, that striping in Camellia japonica may depend on 

 the time of flowering. 



