154 BOTANICAL GAZETTE [MARCH 
many of the extra-European plants have been studied either from 
specimens cultivated in botanical gardens or preserved in herbaria. 
This may be the cause why, for instance, the root-structure has not been 
studied to the same extent as that of the other organs, for the root 
system and rhizomes are not satisfactorily represented in herbaria, 
or may be entirely wanting. Also, only a very few of the more com- 
mon genera and species of the North American flora have been studied 
anatomically, because European botanists have not been in a posi- 
tion to study the American plants, and because American botanists 
have not paid sufficient attention to anatomical botany. American 
students, therefore, have an important and interesting task before 
them in undertaking an anatomical investigation of their native 
plants, the common as well as the rarer ones, in order to assist in 
the completion of a work so well begun and so very instructive as 
that of SOLEREDER and his predecessors. 
Moreover, the study of plant structures is necessary to the fuller 
understanding of ecology. The plant societies, so excellently outlined 
by WarMinc and Scuimper, should not be determined merely by 
the social occurrence of a number of types that characterize a certain 
vegetation, but they should be investigated much farther; thus we 
might be able to distinguish between characters that may be looked 
upon as those of the family and those that are purely epharmonic. 
Very frequently, so far as we know, these structural characters do 
not correspond with what might be expected from the nature of the 
habitat. Halophytes and xerophytes are often not to be separated 
by means of their structure alone; for example, many bog plants exhi- 
bit peculiarities that are familiar to us as xerophytic, and vice versa. 
If the structure of all the most significant components of these societies 
was so well understood that we were able to distinguish between 
epharmonic characters and those that are generic or specific, we 
might gain a clearer idea of the real factors that have brought these 
plants together so as to form societies. 
Another and perhaps more important problem is the application 
of the structures as a means of distinguishing genera and species; 
in other words, to bring together such points of distinction as may be 
observed in both the external and internal morphology of plants. 
For this purpose almost any contribution, large or small, may be of 
