256 PSYCHROPHYTES SECT, ix 



CHAPTER LXVII. SUBGLACIAL FELL-FIELD FORMATIONS 



MOST characteristic of the fell-fields 1 is the short stature of the plants 

 (showing nanism) ; also the fact that the soil is never completely covered 

 by plants. One individual stands here, and another there ; between 

 them we see bare, pebbly, stony, sandy, or clayey soil, which is devoid 

 of humus and determines the prevailing colour of the landscape. In 

 eastern Greenland Pansch and Hartz saw places which were so bare that 

 scarcely a moss or lichen was visible. The cause for the poverty in 

 individuals does not lie in the soil itself, for this indubitably contains a 

 sufficiency of nutritive substances and water, and could certainly produce 

 luxuriant vegetation were sufficient heat supplied. Between climate and 

 density of vegetation there evidently must be a certain constant relation 

 of such a kind that no more seeds or other propagative organs germinate 

 or develop into plants than just suffice to maintain the vegetation at 

 the standard once established. Only under specially favourable circum- 

 stances are the seeds capable of germinating and developing into plants. 

 Subglacial species (and lithophytes) may be regarded as the pioneers 

 of the plant-world, since they are least dependent upon other plants 

 or upon animals. 



Another characteristic feature of the fell-field is the abundance of 

 Cryptogamia. These are mainly lichens and mosses at least in the 

 northern and arctic fell-fields ; this is due to the ability these plants 

 have of thriving at low temperatures. Their abundance varies with 

 the situation, and partly according to the soil ; on slate in the North 

 it would appear that the number of Spermophyta is greater than that 

 of mosses and lichens, and the vegetation is more varied ; but the reverse 

 is true on mountains composed of primitive rocks, where the vegetation 

 passes over into the lichen-heath and moss-heath. In addition to these 

 Cryptogamia there occur taller plants, including both herbs and dwarf- 

 shrubs. The Spermophyta mostly assume the cushion-form or tufted- 

 form, and possess a perennial, strong, tap-root (the root or rhizome is 

 multicipital) ; the leaves of herbs usually form a rosette on the ground. 

 The dwarf -shrubs are mostly evergreen. 



The soil varies in nature. In general in Polar countries and on many 

 high mountains it may be described as being one of older or younger 

 moraine-stones : and the vegetation on soil that is very stony accordingly 

 approximates to rock-vegetation, which, indeed, establishes itself here 

 and there in typical form. Elsewhere, clay and sand preponderate over 

 stones and gravel. Various forms of vegetation consequently develop side 

 by side and are intermingled. 



Fell-fields are found upon the highest and most sterile situations 

 on high mountains and towards the Poles as far as the region of perpetual 

 snow and ice. 



The flora of fell-fields may be considerably diversified, and is mostly 

 so because no single species dominates. The species and genera present 

 in different parts of the Earth differ very widely. 



1 German, Felsen-fluren ; Danish, Fj aid-marker; ' Gesteinsfluren ' of Schroter, 

 1904-8, p. 503. 



