24 THE PLANT LIFE OF MARYLAND 



a large mass of data on the topography, geology, soils, climatology 

 and other natural features of Maryland has rendered it a particularly 

 favorable area for the prosecution of such work as is outlined in this 

 volume. 



The study of the plant life of a specified area, as a state or nation, 

 falls naturally into two phases, one dominated by the view-point of 

 systematic botany, the other by that of ecological or physiological 

 botany. The first of these phases, Floristic Plant Geography, has to 

 do with the geographical aspects of the completed work of systematic 

 botany. That is to say, after the describing and listing of all species 

 of plants found growing in the area, Floristic Plant Geography then 

 endeavors to show what families and genera of plants are most abun- 

 dantly represented in species, what are the relationships of the flora 

 to that of neighboring areas, what are the probable sources and paths 

 of migration of the species which have entered the area from without 

 and what are the bounds of distribution of the species not found 

 throughout the area. Such a study is concerned with individual 

 plants only as they go to make up the collective representation of the 

 species. All the plant species of an area considered collectively, and 

 from the systematic view-point, constitute its flora. 



The physiological phase of the study of the plant life of particular 

 areas, Ecological Plant Geography, is not at all concerned with the 

 systematic relationships of plants, but rather with their form, 

 structure and functions, and the relation which these bear to the 

 physical and organic environment of the individuals. Carrying out 

 studies in the Physiological Plant Geography of a region demands a 

 knowledge of the climate, geology, topography and soils, and of the 

 structural and functional characteristics of the plants themselves. It 

 endeavors to answer the questions : what physiological types of plants 

 are dominant in the region, in what manner are the plants associated 

 together and how do these associations vary from place to place; what 

 are the influences of the mineralogical character or the texture of 

 soils in determining the nature of the plant life, and what relation to 

 topography, soil moisture, wind and other factors have to the dis- 

 tribution of the different types of plants and plant associations ? All 

 the plant individuals of an area considered collectively and from the 

 physiological view-point constitute its vegetation. To speak of the 



