180 ANTHOCYANINS AND GENETICS 



CONNECTION OF FLOWER-COLOUR WITH THE PRESENCE OF ANTHO- 

 CYANIN IN VEGETATIVE ORGANS, FRUITS AND SEEDS. 



Such cases are illustrated among the following genera and species: 



Antirrhinum ma jus, Helianthus, 



Atropa Belladonna, Lathyrus odoratus, 



Beta, Oenothera, 



Corchorus capsularis, Pisum sativum, 



Datura, Primula sinensis, 



Digitalis purpurea, Salvia Horminum, 



Gossypium, Zea Mays. 



There appear to be several possibilities in the inheritance of colour 

 in such cases as these we are considering. Colour (anthocyanin) in 

 the plant may be represented by one factor which causes the flowers, 

 as well as other organs, to develop pigment. When this factor is 

 absent, pigment disappears from the whole plant including the flower ; 

 this is perhaps the most common case. Colour, however, may disappear 

 from the flower, or any other organ, independently of the rest of the 

 plant. One of the most striking examples of independent connections 

 of this kind we find in Maize ; the plant may have pigment in the sheath, 

 cob, pericarp, silks, etc., and practically in all or any of these parts. 

 In such a case, if colour in each part is represented by a separate factor, 

 we should expect by crossing suitable plants to obtain all the Mendelian 

 combinations. This, however, is not always so, as for instance in Maize 

 (Emerson, 554), and a number of other plants. The lack of some 

 combinations may be due either to reduplication phenomena (see 

 p. 185), or to some form of genetic correlation, and to decide between 

 these alternatives often involves further data than we have at present. 

 In the following genera indication is given of such colour relationships 

 as we know to exist: 



Antirrhinum majus. The white ; ivory and yellow-flowered varieties 

 never produce anthocyanin in any part of the plant. The author 

 has noticed that the stems and leaves of deep magenta- and crimson- 

 flowered varieties produce anthocyanin to a considerable extent, 

 whereas in intermediate and pale varieties these organs are practically 

 free from anthocyanin. 



Atropa Belladonna. The type has anthocyanin in the flowers 

 (brown), fruits (black) and stems (tinged with red). The albino has 

 yellow flowers and fruits, and a green stem (Saunders, 475). 



