260 STUDY OF COMMON PLANTS. 



late autumn, that there is no diiSculty in obtaining abun- 

 dant material. With patience and close attention to 

 details of structure, there is no reason why the student 

 should not become thoroughly familiar with the charac- 

 ters of this important and extremely interesting family, 

 although the determination of the limits of genera and 

 species is often a matter of great difficulty, owing to the 

 number of intermediate forms and the tendency to vari- 

 ability exhibited by many species. 



When as many species have been studied as the time 

 will permit, write a careful summary of the morphological 

 characters in which they all agree. This should be accom- 

 panied by a resume of their physiological peculiarities, 

 especially the arrangements for securing fertilization and 

 the dispersal of seeds. 



The Compositse constitute the largest family of flower- 

 ing plants, including over one thousand different genera. 

 Admirably fitted to survive in the struggle for existence, 

 they have become distributed throughout the world, and 

 retain tenaciously their dominant position. Some of the 

 genera are represented by so many species, and are so 

 abundant as to form in their season a characteristic feature 

 of the landscape, as is the case, for example, with the 

 asters and goldenrods in eastern North America. "The 

 numerical preponderance, . . . and extreme abundance of 

 many of the species, are due to the concurrence of several 

 characters, most of which, singly, or in some degree com- 

 bined, we have become acquainted with in other families, 

 but never in such happy combinations as in the Com- 

 positae." See Miiller's discussion of these points in the 

 Fertilization of Flowers, p. 316 et seq. 



