154 INTRODUCTION TO BOTANY 



occurs in the flowers of bluets (fig. 138), the partridge berry, 

 the primrose, and some other common flowers. It is easy to 

 see that the tongue of an insect smeared with pollen by contact 

 with the anthers of figure 138, A would just come into contact 

 with the stigma of It, and that the insect's abdomen covered 

 with pollen in B would just touch the stigma of A. All the 

 flowers on an individual plant are of one kind (either long- 

 styled or short-styled), and the pollen is of two sorts, each 

 kind sterile on the stigma of any flower of similar form to that 

 from which it came. 



On the general subject of pollination of flowers and illus- 

 trations of special cases see 



DARWIN, The Effects of Cross- and Self-Fertilization in the Vegeta- 

 ble Kingdom. D. Appleton and Company, New York. 



DARWIN, Different Forms of Flowers on Plants of the Same Species. 

 D. Appleton and Company, New York. 



DARWIN, The Various Contrivances by which- Orchids are fertilized 

 by Insects. D. Appleton and Company, New York. 



GRAY, Structural Botany. American Book Company, New York. 



KKRNER-OLIVER, Natural History of Plants, Vol. II. Henry Holt 

 and Company, New York. 



KNUTH-DAVIS, Handbook of Flower Pollination. Clarendon Press, 

 Oxford. 



WEED, Ten New England Blossoms. Houghton Miffliu Company, 

 Boston. 



PROBLEMS i 



1. Of what use to the plant are flowers? On what grounds would 

 you decide which of two flowers serves this purpose more effectively? 



2. In a general way, are the flowers discussed in the earlier or the 

 later sections (sects. 130-145) more perfectly equipped for successful 

 pollination ? 



3. If the lowest types of flower came earlier than the highest ones, 

 what kind of pollination probably characterized some of the first flower- 

 ing plants that appeared on the earth ? 



4. Why does a corn plant growing alone seldom produce good ears? 



1 These problems are to some extent based on the statements in regard 

 to floral structures given in Chapter IX. 



