Nov. 1909.]| BOTANICAL SOCIETY OF EDINBURGH 55 
plant-function and is related to plant-geography on the one 
hand, and plant-physiology on the other; hence has arisen 
the branch of Physiological Plant-geography. This 
attempts to explain the presence of plant species and the 
occurrence of growth-forms from the conditions of the 
environment. Some authors, such as A. F. W. Schimper 
(“Plant Geography,” 1903), take up primarily the relation 
between plant-distribution and the factors of soil and 
climate. Other authors, notably Warming (“ C&icology of 
Plants,’ 1909), are more concerned with the relation of 
plant-form to environment, and assuine as a postulate that 
similar conditions of environment produce a similar plant- 
form. Other subdivisions of the subject also appear from 
the works of various authors: some take up the distribu- 
tion and ecology of single species, others follow out plant 
communities.! 
The ideal botanical survey of a district or country should 
take account of all these points of view of plant-geography 
—floristic, distributional,and ecological,—andinall directions 
something has been done, but much remains to be done yet. 
The British memoirs which have used the term botanical 
survey in their titles are now fairly numerous (see list at 
the end of this paper). When analysed broadly, they will 
be found to deal with plant communities rather than with 
single species, and the relation to environment receives a 
prominent place. The stages of the work can in most cases 
be resolved into four processes :— 
(a) Selection of an area—This has generally been some 
district fairly accessible to the author, so that with fre- 
quent opportunity of imspecting the vegetation in all its 
seasonal phases one may expect a fairly accurate know- 
ledge, even of a large district. The selected areas also 
contain, as a rule, a large proportion of vegetation little 
influenced by man’s activities, and, as far as possible, large 
tracts of farmland and city areas are avoided. 
(b) Analysis of vegetation into its wnits—The larger 
masses of vegetation are recorded, and here a map is in- 
dispensable, and this map in a reduced form appears in the 
1 The term “plant community” is used here as an indifferent desig- 
nation for any set of plants growing together; it is equivalent to the 
use of “group” in systematic botany. 
