THE FLOE A 413 



occurrence which I found in such situations are : Oxytropis 

 campestris (rare), Arctostaphylos alpina, Loiseleuria pro- 

 cumbens (rare), Vaccinium uliginosum, V. Vitis-Idcea, var. 

 minus, Diapensia Lapponica (growing in little rounded 

 mounds on its own previous growth, very branchy, showing 

 yearly additions outward and upward, one specimen I 

 examined was three inches in diameter and one and a half 

 inches high in the centre) ; willows, Empetrumnigrum, Carex 

 rigida (rare), Festuca brevifolia (rare); three mosses (Di- 

 cranum, Polytricum strictum, Racomitrium lanuginosum) , 

 and a lichen (Umbilicaria) . Dead roots and branches, 

 especially of the willows and Ericaceae, were frequent, and 

 on them grew other varieties of moss. Labrador tea and 

 grasses flourished on the edges of these bare patches, where 

 some soil had already been formed. 



(c) " Shallow depressions of the tundra, where the water 

 of melted snow and ice accumulates in the soil, become 

 swamps in the form of tundra-moor, and there a scanty peat 

 bears a thin layer of sphagnum with a few small phanero- 

 gams. Such places correspond physically but not physi- 

 ologically to the oases of the dry desert" (Schimper). 

 The moor presents many features that are unfavourable to 

 the life of plants. Humous acids are abundant and pre- 

 vent the easy absorption of moisture; mineral substances 

 are hard to obtain, " owing to the great distance of the vege- 

 tation from the mineral substratum and to the absorptive 

 influence of humus, rendering it difficult for the plants to 

 obtain soluble salts"; nitrogen is abundant, but in such 

 form that the moor is among the poorest of soils in easily 

 assimilable nitrogenous substances. Sphagnum is the 

 characteristic and most abundant plant in such situations. 



