Ch.VIII] COLD TEMPERATE GRASSLAND FORMATIONS 593 



interrupted by bare spaces ; yet there are, especially in North America, 

 steppes that are very thickly overgrown and yet decidedly xerophilous. 

 The grasses usually grow in tufts, but there are also creeping species, 

 and they it is which usually produce completely covered steppe — for 

 example Buchloe dactyloides in North America (Fig. 336). During winter 

 the superficial part of a typical steppe, in opposition to that of a meadow, 

 is for the most part dried up. Wherever mid-summer is rainless, desiccation 

 may set in even then. 



2. THE VEGETATION IN MEADOW DISTRICTS AND 

 STEPPE DISTRICTS. 



i. MEADOW. 



Natural meadows apparently occupy less extensive areas than do natural 

 steppes, and they chiefly appear in transitional climatic districts whose vegeta- 

 tion is park- like in character, that is to say, where grassland and patches of 

 forest alternate with one another. This is due to the fact that the moister 

 meadow climate is more favourable to growth of trees than is a true steppe 

 climate. 



Possibly the natural plant-covering of Europe exhibited such a park-like 

 physiognomy. The European climate is neither a pronounced woodland 

 climate nor grassland climate, but equally favourable to both formations ; 

 and the occurrence of numerous plants that are absent from the flora of the 

 forest is in favour of the former existence of natural meadow. Such natural 

 meadows, however, exist no longer, even where they occupy an original 

 meadow-area. Mowing, grazing, manuring, and other operations have 

 certainly fundamentally modified the original appearance of a European 

 meadow. Hence no attempt will be made to give a detailed description 

 of a Central European meadow l . 



Luxuriant virgin meadows occur in the parkland tracts by the Amur, 

 in Kamchatka (Figs. 237, 325), and on the island of Saghalin (Figs. 323, 

 326). In them many herbs, especially species of Umbelliferae and Spiraea, 

 exhibit the greatest luxuriance and are often taller than a man. Apparently, 

 as in transitional climatic districts in general, slight differences in the soil 

 determine the alternation of the two forms of vegetation : a more porous 

 soil, or one that is moister owing to lateral infiltration into lower levels, 

 will produce woods ; one less permeable and only superficially moist, patches 

 of grassland. No definite information on this question is, however, available. 



The most extensive natural meadow district is probably that of the 

 eastern prairie in North America, yet it has often been stated 2 that it was 



1 Excellent descriptions are given by Drude, op. cit., p. 339 ; by Stebler and Schroter, 

 op. cit. ; and by Weber, op. cit. 



2 See Mayr, op. cit., p. 231. 



SCHIMPER Q Q 



