326 SOME SPECIAL ADAPTATIONS 



with the seeds, the latter passing through the body un- 

 harmed (strawberries, grapes, and most berries). Many- 

 small, rounded seeds dropping to the earth are widely 

 distributed by animals to whose feet the earth containing 

 them clings, thus being carried long distances. Such are 

 the majority of the common weeds of the roadsides, 

 barnyards, and waste places (pigweeds, lamb 's quarters, 

 purslane, knot-grass, etc.). Of special interest, but rela- 

 tively infrequent, are the plants that have fruits that 

 dehisce explosively so that their seeds are flung compara- 

 tively long distances, thus placing them where they do 

 not compete with their parents (OxaHs, touch-me-not, 

 various vetches, wild geranium, etc.). 



REFERENCE BOOKS 



W. F. Ganong, The Living Plant, New York, 1913. 



F. E. Clements, Plant Physiology and Ecology, New York, 



1907. 

 H. C. CowLES, Ecology (in Textbook of Botany by Coulter, 



Barnes and Cowles) Chicago, 1911. 

 Hermann Muller, The Fertilization of Flowers, Engl. Ed., 



London, 1883. 

 Paul Knuth, Handbook of Flower Pollination, Engl. Ed. 



Oxford, 1906-9. 

 Eng. Warming, Oecology of Plants, Engl. Ed., Oxford, 1909. 



