SOCIAL LIFE AMONG PLANTS 



15 



quadrats the nuiuucr of seedlings can be counted (Fig. 7). Ochsner 

 (1928) for years followed the competition of bark mosses and hchens 

 by means of annual sketches showing displacements of the tussocks and 

 tlisiius borders and the periods of inactivity (Fig. 8). Sometimes 

 photographs give excellent data. 



Overestimation of the Factors of Competition. — When a new and 

 important viewpoint enters a science, its significance is often over- 

 valued, not rarely leading to error. For instance, it has been claimed 

 that the occurrence of nearly all plants is rather independent of soil 

 conditions but depends on competition and the competitors (Warming- 



Fio. 7. — Pcrnianont rinadrat (1 scj. in.) lor srcdinifi cnuui.s ui. .-in open area in the 

 Rosmarinus-Lithospcrrnum fruticoswrn association near Montpellier, France. {Photo 

 by Braun-Blanqnet and Keller.) 



Graebner, 1918, p. 126; Cajander, 1926). It is pointed out that in 

 botanic gardens plants from the most diverse climates and soils grow 

 harmoniously side by side. The thing that is not mentioned, and 

 mostly not investigated, is whether they continue to produce viable 

 offspring and maintain themselves without renewed planting. In 

 many cases they certainly do not. 



It has further been said that certain species are in general confined 

 to certain soils, but when they come into competition one wins on 

 calcareous soil, the other on siliceous soil, K. Nageli cites Achillea 



