250 



PLANT-BREEDING 



their coats. By this means the improved variety may be 

 distinguished by the marks of the flowers. 



Besides their color, the foHage and the flowers may be 

 correlated in their form. The most striking instance is 

 that of those varieties which have laciniate leaves and 

 repeat the same character in their petals. Two notable 

 plants give proof of tliis assertion. One of them is the lacin- 

 iate form of the ordinary celandine, and the other a variety 

 of the common bramble. Its petals are divided into three 

 equal lobes, which in their turn may show small incisions 

 at their top. These are evidently analogous to the repeated 

 divisions of the lobes of the leaves. 



All the cases hitherto given were related to homologies 

 between flowers and other organs. But even within the 

 flowers correlations may be observed. They arc of numer- 

 ous patterns, but I must limit myself to one instance. As 

 such I choose the size of the flowers and the relative length 

 of the style and the stamens. 



It is a fact of daily observation that many small flowers 

 do not need the help of insects for their fertilization. In a 

 large number of cases their stamens directly touch the stig- 

 ma, and the pollen is spread over it by the very act of the 

 opening of the anthers. Many of our common species of 

 the large family of the cruciferous plants give instances of 

 this. On the other hand, great size in flowers is often com- 

 bined with the production of stigma and anthers at such a 

 distance that the pollen can only reach the first by the aid 

 of bees and other visitors. 



In the evening primroses, as in many other plants, the 

 size of the flowers depends upon the season in which they 

 open. This dependence may go so far as to change the whole 

 biological aspect of the flower. In the ordinary sorts of the 

 evening primroses (CEnothera biennis and allies), the style 

 is short and the anthers are arranged around the stigma. 



