396 Origin of Each Species Considered Separately. 



their greatest breadth is about their middle or sHghtly 

 above this and they are rounded at the tip. They are 

 very hke the autumn flowers of 0. laevifolia. (Fig. 59, 

 p. 312), only that they have this shape from the be- 

 ginning of the flowering period. And just as the shape 

 of the petals in laevifolia in autumn may be ascribed to 

 the diminished supply of nutriment at that time of the 

 year, so there is very probably some causal relation be- 

 tween the shape of the petals and the narrowness of the 

 leaves in 0. elliptic a. 



The pollen w^as frequently empty, but this also hap- 

 pens occasionally in other species as in O. scintillans and 

 even in O. gigas. It is quite normal for numerous species 

 of Oenothera to have a large proportion of sterile pollen, 

 as for example in O. biennis L. and O. niuricata L. The 

 fruits of elliptica were small, and contained little seed. 



The origin of 0. elliptica has alread}^ been noted in 

 the pedigrees of the various families (Part II, §§1-7). 

 Here is a summary of these cases : 



FAMILY YEAR NUMBER OF O. ELLIPTICA 



O. Lmnarckiana, a branch 



of the main family, 1895, 1896 8 



O. laevifolia 1889, 1891, 1893, 1894 7 



O. lata 1900 1 



O. lata 1890 2 



I have not entered the occurrence of 0. elliptica in 

 the pedigree of the La/warc^fana- family (p. 224) ; its 

 occurrence in the various years in which it appeared was 

 as follows : 



YEAR NUMBER OF O. ELLIPTICA 



2nd Generation 1888 2 



3rd " 1890 2 



6th '• 1896 7 



