POLLINATION AND FEETILIZATION 135 



usually before maturing become partially buried in the earth. 

 The cleistogamous flowers produce many more seeds than the 

 showy ones, but the latter insure occasional cross-pollination.i 



1 On the general subject of pollination of flowers and illustrations of 

 special cases see : 



Knuth-Davis, Handbook of Flower Pollination. Clarendon Press, Oxford. 



Darwin, The Effects of Cross and Self Fertilisation in the Vegetable 

 Kingdom. D. Appleton and Company, New York. 



Darwin, Different Forms of Flowei-s 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. 



Kerner-Oliver, Natural History of Plants, Vol. II. Henry Holt and Com- 

 pany, New York. 



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



Weed, Ten New England Blossoms. Houghton MifElin Company, Boston. 



