OENOTHERA LAMARCKIANA MUT. VELUTINA. 163 



The flowers of 0. blandina are cup-shaped, whereas those of the 

 parent species are more or less quadrangular. The size is the same, 

 the color is as bright, and the stamens show no marked difference; 

 the supply of pollen is very large in both cases. The stigma is widely 

 spread out above the anthers, the distance being even somewhat 

 larger in the mutant (1 cm. against 0.5 cm.). The flower buds are 

 almost twice as thick in the mutant, more regularly and more 

 deeply colored with red brown lines and spots, and much more 

 hairy. This color and this hairiness extend over the tube of the 

 flower and the ovary, and in a less degree over the top of the stem 

 and the young bracts. The small free tips at the top of the flower 

 bud are thick in 0. blandina but thin in 0. Lamarckiana. The diffe- 

 rences of the fruits are small, except for the hairiness. The most 

 striking character of 0. blandina, however, is seen at the end of the 

 flowering period, when the spikes are long and the lower fruits 

 begin to ripen. At that period the spikes are very slender, with few 

 fruits and long internodes, whereas on the spike of 0. Lamarckiana 

 the fruits are densely crowded. I counted the fruits on a length of 

 half a meter in the middle part of the spike, at the end of September, 

 and found 30 of them on 0. blandina, but 75 on 0. Lamarckiana, 

 both on very vigorous annual specimens. From this the internodes 

 of the spike are 1.7 against o.7 cm., or more than twice as long as 

 those of the parent species. The average numbers of flowers which 

 open on a spike during an evening are inversely proportional to 

 these figures. For many crosses I have castrated five successive 

 flower buds of 0. Lamarckiana on one day and pollinated them the 

 next day, whereas the crossing of 5 flowers on a spike of 0. blandina 

 usually lasts 4 or more days, which makes quite a difference in the 

 technical work. 



Of course, there are a number of distinguishing points of less 

 value, but their description would remain vague unless strict averages 

 could be given; and since all characters are more or less dependent 

 upon the conditions of soil and culture, it is doubtful whether even 

 averages would be reliable. I shall return to this point in the descrip- 

 tion of the hybrids. 



In comparing this description with that given in my book on 

 Gruppenweise Artbildung for 0. (Lamarckiana x 0. biennis Chicago) 

 velutina, it will easily be seen that the two belong to the same type. 

 In the garden, when groups of 10—30 plants are compared, this 

 similarity is of course far more striking. It is at once clear that 0. 

 blandina must be a true and pure velutina. 



