292 PLANTS OF NEW ZEALAND 



may be found in the pollen grains of the evening primrose, 

 Godetia, ClarMa, and some species of Epilobium. 



All the New Zealand forms of the genus Fuchsia are 

 endemic, and the only other known species come from South 

 America and Mexico. Thus our Fuchsias well illustrate the 

 former connection existing between New Zealand and South 

 America (v. Introduction p . 36). 



But, for botanists, the chief interest of the New Zealand 

 forms lies in the methods by which cross-pollination is attained 

 It has long been known that in flowers of certain plants, 

 dimorphism or trirnorphism exists, i.e., stamens and styles are 

 found of two, sometimes of three different lengths. It was 

 not, however, until Darwin had investigated the matter, that 

 a complete explanation of these variations of form was forth- 

 coming. In his work on the " Forms of Flowers " he has 

 dealt with this subject very fully. The common English 

 meadow primrose is the first plant which he discusses, and it 

 is usually taken as the type of a dimorphic flower. If a number 

 of primrose flowers are examined, it will be found that in 

 some the anthers are placed at the top of the corolla tube, and 

 in others they are attached inside the tube half-way down its 

 length. Those flowers which have the anthers at the rim of 

 the corolla tube, have a style which is concealed within the 

 tube, and the other flowers, with the short stamens, have a 

 style which protrudes from the tube. In other words, long 

 stamens go with a short style, and vice versa. Now a bee 

 pushing its way into a flower with short stamens, gets the 

 pollen on to its tongue, but, if it goes into a flower with long 

 stamens, the pollen sticks to its head. The pollen from its head 

 can clearly only be placed upon the stigma of a flower with a 

 long style, while that from the tongue, must, on the other hand, 

 be placed upon the stigma of a flower with a short style. 

 Thus cross-pollination is inevitable. It has further been shown 

 that the primrose is less fertile with its own pollen, so that its 

 perpetuation is largely dependent upon the presence of insects. 



