686 ZONES AND REGIONS [Pt. Ill, Sect. Ill 



ice accumulates in the soil, become swamps in the form of T?nidra-vwor,2LX\d 

 there a scanty peat bears a thin layer of Sphagnum with a few small pha- 

 nerogams. Such places correspond physically but not physiologically to 

 the oases of the dry desert. The physiological analogues in the tundras of 

 the desert oasis are Heat-oases — sunny slopes protected from the drying 

 winds — upon which the sunbeams fall almost perpendicularly, and thus warm 

 the water in the soil so that plants can obtain it in actual abundance. Such 

 stations frequently resemble the flower-beds of a garden 1 . 

 According to Nathorst 2 : — 



' The plants of the slopes are in many respects the most interesting. The majority 

 of them occur as strongly developed individuals, which here appear to thrive per- 

 fectly, and apparently can ripen their seed annually. This naturally is true of the 

 good localities, namely of the slopes that soon become free from snow. Here one 

 has an opportunity of being able to observe the remarkable influence of the sun's 

 rays. Slopes, that a short time before were covered with snow, a few days later are 

 adorned with several flowers ; the development of these can proceed so rapidly 

 that one soon finds fruit as well, as in the case of Draba. Here one sometimes sees 

 quite blue mats of Polemonium pulchellum, or red ones of Saxifraga oppositifolia, 

 with a varied mixture of other tints, yellow, white, green. . . . When the plants of 

 the slopes occur in the plains, they are not usually so well developed as on the 

 slopes, but the difference in this respect is much greater in some plants than in 

 others.' 



Middendorff gives the following description of the dry tundra in 

 Taimyr 3 : — 



' On the dry firm soil of the deeply undulating land, a meagre vegetation obtains 

 a footing, unable to cover the loamy sandy gravel, which serves as a substratum. 

 Mosses and sedges about half-cover the surface, which, as it is overgrown only in 

 patches, and not uninterruptedly like our meadows, seems to be studded with little 

 hillocks. The mossy covering of the high, dry Polytrichum-tundra, as I have termed 

 it, is chiefly composed of several species of Polytrichum, Bryum, and Hypnum, some- 

 times of numerous species of Hypnum. From the dingy yellowish-brown mossy 

 surface, resembling as it does a flat network of furrows, patches of sedge rise like 

 hillocks, but the burnt yellow tops of the rushes, reeds, and cotton-grass, already 

 half-dead at the commencement of summer, stand out but inconspicuously from the 

 ground colour of the carpet of moss ; the lower and greater part of the sedge reveals 

 itself but indistinctly, as if through a veil, because as true spring plants the sedges 

 have prepared their inflorescences in the preceding summer, and are in full bloom 

 at the beginning of the extreme northern summer (July ioth-2oth), and are turning 

 brown when the true grasses are only beginning to form their buds. 



'On tracts that are uniform orographically, the forbidding appearance of the 

 tundra becomes one of the most barren monotony. ... No variety, no shade, no 



1 See Kjellman, op. cit., p. 462. 2 Nathorst, op. cit., p. 444. 



3 Middendorff, op. cit, p. 730. 



