102 Inheritance in the Cowpea 



I. Flower Colour. 



There are three principal types of flower colour in the cowpea. 

 These may be described briefly as follows : 



Dark. Possessing much anthocyanin coloration, producing a flower 

 the prevailing colour of which is a more or less deep reddish violet. 

 Colour is most developed in the region of the throat and on the wings. 

 The keel is usually without colour, but a slight amount of violet streaking 

 may be present. 



Pale. Distinguished from the Dark form chiefly in the lesser de- 

 velopment of anthocyanin coloration. The standard is almost white 

 but the wings are faintly streaked with violet. The keel is devoid of 

 colour. 



White. Anthocyanin colour entirely absent, the flower being pure 

 white except for a faint primrose tinge on the standard in the neighbour- 

 hood of the throat. 



(1) Dark by Pale. 



Several reciprocal crosses were made. The flower colour of the first 

 hybrid generation was in all cases indistinguishable from that of the 

 Dark parent. Dark is thus completely dominant over Pale. 



The F^. 



In the F2 three groups of families were grown. The numerical 

 results are presented in Table I. A survey of them shows that segre- 

 gation occurs into Dark and Pale. The ratio of Dark to Pale is the 

 simple Mendelian one of 37) to IP. 



TheFs. 



In the Fs a large number of families were grown. The results are to 

 be found in Tables II, III, and IV. From these results it will be seen 

 that in F3 some of the Darks bred true, while others segregated into 

 Dark and Pale in the 3 — 1 ratio. The Pales, with certain exceptions 

 explained below, bred true. 



Gametic contamination of the F. results through Natural Grossing. 



The ^3 families of cross 1 from F^ parents with Pale flowers all bred 

 true. With the exception of one family, this was also true of the 

 families of cross 2. In cross 5, 71 families from F^ Pales were gro\vn. 

 14 of these families contained Darks, but in small numbers. At 



