242 THE STORY OF PLANT LIFE 



slender, with narrow leaves and bright flowers ; the 

 short-styled form is larger, coarser, very downy, with 

 dull purple flowers. The three forms have the 

 following arrangements : a long style with medium 

 stamens, medium-sized yellow pollen, and short 

 stamens with small yellow pollen ; medium style 

 with long stamens and large green pollen, and short 

 stamens with small yellow pollen ; a short style with 

 long stamens and large green pollen, and medium 

 stamens with medium yellow pollen. 



By these arrangements eighteen modes of cross- 

 pollination are rendered possible. The seeds of the 

 three forms, long, medium, and short styled, differ 

 in number, being in the proportion of lOO, 121, 142. 

 Unless the flowers are cross-pollinated by insects 

 the plant does not set seed. Being a conspicuous 

 flower with honey it is much visited, however, by 

 bees, humble-bees and flies, which alight on the 

 stamens and pistil. The long-styled form must be 

 fertilised with either of the long-stamened forms 

 for the most perfect results, and is imperfectly 

 pollinated by the shorter-stamened forms or by its 

 own short stamens. In the two former cases pollina- 

 tion is legitimate, in the four latter illegitimate, and 

 of the eighteen modes of pollination possible six are 

 legitimate, twelve illegitimate. 



The fruit or capsule opens down the centre of each 

 valve and bursts irregularly. The seeds are small, 

 numerous, plano-convex, yellow, testaceous, nearly 

 smooth, and float|in water. 



