POLLINATION AND FEKTILIZATION 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. 1 



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 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. 



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 Mifflin Company, Boston. 



