36 



PLANT SOCIOLOGY 



and thus cover the ground in patches or are wholly isolated and stand 

 scattered among each other in motley mixture." Heer expressed the 

 degree of association by the figures 1 to 10. Lecoq (1854) (who, how- 

 ever, used the term "sociability" with a somewhat different meaning) 

 and Lorenz (1858, p. 227) also concerned themselves with the gregari- 

 ousness of species. 



Fig. 15. — Chrysosplenumialtcrmfolium (Soc. 4) Frankfurt-on-Oder. {Photo by Hueck.) 



Gregariousness or "sociability" expresses a space relationship of 

 individual plants, answering the question, How are the individuals or 

 shoots of a species grouped? 



To describe the grouping we use the following scale : 



Soc. 1 = growing one in a place, singly. 



Soc. 2 = grouped or tufted. 



Soc. 3 = in troops, small patches, or cushions. 



Soc. 4 = in small colonies, in extensive patches, or forming carpets. 



Soc. 5 = in great crowds (pure populations). 



The density of the stand of individuals or shoots is indicated by a 

 dotted or solid line under the figure. Thus Typha minhna (Soc. 5) 

 means an open but large patch of Typha minima, and Calluna (Soc. 5) 

 indicates a large, dense, closed stand of heather (Figs. 13 to 15). 



Only a few plants have a predetermined unchangeable degree of 

 aggregation of individuals or shoots (sociability) based upon the 



