Ch.VIII] COLD TEMPERATE GRASSLAND FORMATIONS 6oi 



be surpassed at all in this respect, it is only by Artemisia austriaca, Xanthium 

 spinosum, and Amaranthus retroflexus, of which the first two cover whole tracts 

 in dense pure masses, the first giving preference rather to the high-steppe, the 

 second rather to the lower parts of the slopes. Owing to the social growth and 

 the relatively not inconsiderable size of the individual plants, they render them- 

 selves more noticeable than other plants— such, for instance, as Atriplex laciniata, 

 Polygonum aviculare, Portulaca oleracea, and Eragrostis poaeoides — are able to 

 do in spite of the enormous number of their individuals. . . . 



'The following plants also influence the character of the autumnal vegetation 

 on account of their great abun- 

 dance : Taraxacum serotinum, 

 Achillea Millefolium, Polycne- 

 mum arvense, Artemisia campes- 

 tris and A. scoparia, as well as 

 A. Absinthium, Chenopodium 

 opulifolium, Atriplex nitens, A. 

 rosea, and Kochia prostrata, 

 which are sufficiently numerous 

 but not present everywhere. . . . 

 The species of Euphorbia (E. 

 nicaeensis), however, again play 

 an important part, because, 

 though but rarely adorned with 

 flowers, they contrast agreeably 

 by means of their relatively 

 bright green tints with the uni- 

 form grey of the dominant plants. 

 In September and October this 

 grey tint is mingled with the 

 fresh green of the sprouting 

 grass.' 



The transition in South 

 Russia from the forest district 

 to the steppe district is de- 

 scribed as follows by Reh- 

 mann 1 : — 



Fig. 337. North American prairie-flora. Munroa 

 squarrosa, Torr. Natural size. From a specimen in the 

 Berlin Herbarium. 



' The natural boundary of the 

 steppe district is indicated by oak- 

 woods ; the course of this boundary line is, however, not everywhere uniform, and 

 the forests penetrate most deeply into the steppe district along the beds of 

 the Dniester and the Bug. . . . 



' Along the whole of this line the forests occur in small scattered blocks ; and, 

 almost everywhere that I have seen, their existence is associated with valleys and 

 deeper ravines ; they cover the inner banks of these depressions, and do not usually 



1 Rehmann, op. cit., p. 47. 



