Mutations in Other Families. 



293 



were pure, that is to say each species in each culture was 

 raised from seeds of that species : this made it easy to 

 choose a good average form of leaf. 



The most easy to recognize are O. nancUa (Fig. 52n) 

 and 0. lata (Fig. 52/). The former has rather short- 

 stalked slightly undulating leaves with hroad ]:)ases; the 

 result being that the leaves have the appearance of being 



Fig. 52. Fully grown leaves of young rosettes in June. L, 

 Oenothera Lamarckiana ; n. O. nanella; g, O. gigas; r, 

 O, rubrinervis ; I, O. lata; s, O. scintillans. 



much crowded in the heart of the rosette. The latter 

 has long-stalked leaves whose apices are quite round. 

 Their surface is very uneven but their margin is fairly 

 level and tears very easily if one attempts to press the 

 leaf flat (hence the small tear at the tip). O. gigas is 



