CLIMATIC ZONES 37 



The northernmost forest belt is made up of Larch with an inter- 

 mixture of pines and birches, and some spruce. Open areas are 



covered with tundra vegetation of quite arctic aspect, with char- 

 acteristic low evergreen shrubs — Ledum, Andromeda, Rhodo- 

 dendron, and various others — among them the pretty twin-flower 

 (Linnaea). Upright herbaceous plants with showy flowers — lark- 

 spur, aconite, geranium, and others — are abundant, as they are 

 elsewhere in the sub-arctic and alpine regions. 



Central Siberia, including the regions about Lake Baikal, is a 

 country of lofty mountains, and typical Siberian flora mingles 

 with that of the steppes of Turkestan and Mongolia. Owing to 

 the greater moisture of much of this mountain region, as well as 

 its proximity to the regions to the south, there is a more varied 

 vegetation than elsewhere in Siberia. Vegetation extends high 

 up in the mountains, plants having been collected at altitudes of 

 3000 to 3200 metres. 



In western Siberia is a steppe region similar to that of southern 

 Russia and the regions about the Caspian and Aral seas, but it 

 is neither so dry nor so hot as in the latter regions. 



The soil varies, being sometimes a black loam, sometimes sandy 

 clay, and in some places alkaline. 



This " birch-steppe" is so called from the groves of birches and 

 alders which are scattered over it, somewhat like the " oak-open- 

 ings" of the eastern prairies of the United States. These groves 

 become more abundant and luxuriant in the cooler and moister 

 climate of the north, while along the streams poplars and willows 

 grow, and the dry steppe is replaced by prairies and bogs, which 

 support a luxuriant growth of grasses and other herbaceous plants, 

 including such showy flowers as Turk's-cup lilies, yellow day- 

 lilies (Hemerocallis), anemones, and others. A giant umbellifer, 

 Heracleum barbatum, is conspicuous, and much like the American 

 " cow-parsnip " (B . lanatum). 



Eastward from the Altai region the climate is a very severe 

 one, and the vegetation correspondingly scanty. 



The Kamtchatka peninsula forms a special province of the Sibe- 

 rian flora, and because of the effect of the ocean, has a much milder 

 climate and more abundant vegetation than the adjacent mainland. 



Especially interesting is the evident relationship of many species 

 with those of Pacific North America. 



