CLIMATIC ZONES 33 



me-nots and anemones. A knot-weed (Polygonum) and dock 

 (Rumex domestica), have fleshy roots which are used by the natives 

 for food. 



The tundra region of Alaska and northern Canada, differs 

 from the Siberian tundra in a much greater development of lichens, 

 which take the place of the mosses which characterize the latter. 1 

 Two species of lichens, Cetraria islandica and C. cucidlata, the 

 so-called "reindeer moss," cover extensive tracts of land, and 

 serve as the principal food of the herds of reindeer which abound 

 in this region. With these lichens, as in the moss-tundra, are 

 various prostrate shrubs, most of which are identical with those 

 of the Siberian tundra, but one striking species, Kalmia glauca, 

 is not found outside America. 



Meadows of coarse grasses are also found in places, and in favor- 

 able localities a display of showy flowers, including a " shooting 

 star' (Dodecatheon), one of the primrose family, especially 

 developed in Pacific North America. 



The barren islands to the north have a very meagre flora, the 

 greater number of species being grasses. 



Greenland and the adjacent regions have been more thoroughly 

 studied than any other part of the arctic zone and belong rather 

 to the Scandinavian region than to America. The southern part 

 of this area is sub-arctic, and contains a good many species which 

 hardly cross the arctic circle. One of these, the twin-flower, 

 (Linnaea borealis), just reaches the arctic circle in places, and 

 Drude 2 suggests that the northern range of this classical species, 

 should be taken as the boundary between the arctic and sub- 

 arctic zones. 



In the sub-arctic region, thickets of willows, and in the south, 

 alders, are a prominent feature of the vegetation. There are 

 extensive moors covered with dwarf shrubs, and barren rocky 

 formations where little grows except lichens. Grassy moorlands 

 and peat-bogs occupy the more level land between the mountains 

 and the sea, and the sandy shores are mainly occupied by a grass, 

 Elymus arenarius. 



Willow thickets occur as far north as 70°, and some of the 

 herbaceous plants, e. g., Archangelica, especially in the southern 

 portions, are of considerable size, and associated with hawkweed 



1 Drude, loc. tit., p. 357. »Ibid., p. 358. 



