STANDLEY — FLOKA OF GLACIER PARK. 247 



The species marked with an asterisk are nearly or altogether con- 

 fined to this belt, while the others are abundant elsewhere as well. 

 It is evident that very few species are peculiar to the Hudsonian 

 Zone. 



The flora of the zone is much the same wherever it is found, and 

 there are no localities in it of exceptional interest. The plants can be 

 studied easily at Granite Park, Iceberg Lake, Sexton Glacier, Gun- 

 sight Lake, Sperry Chalets, and many other localities. 



ARCTIC-ALPINE ZONE. 



The Arctic-Alpine Zone includes all vegetation above the Hudso- 

 nian, and covers all the slopes above 1,800 to 2,100 meters (see pis. 

 43, 44). In mountain regions in general the plants of this zone are 

 found only about the higher summits, but in Arctic regions the same 

 species grow at sea level. The species are more widely distributed 

 than those of any other division and m9,ny of the characteristic plants 

 of the higher levels of Glacier Park are found also in Europe and Asia. 

 Vegetation extends to the summits of some of the peaks of Glacier 

 Park, but on others it ceases far below the summits. In places plants 

 grow close to the sides of the glaciers and snow banks, but often there 

 are wide stretches of rocks and gravel upon which no vegetation 

 exists. 



It is impossible, as stated above, to draw a sharp line between the 

 Hudsonian and Arctic-Alpine zones. The latter region is composed 

 of wet meadows, of rocky slopes of loose stones with a large amount 

 of soil between them, of areas of exposed rock in place, and of great 

 sUdes of loose rock in which there is little or no soil. In the meadows 

 especially it is difficult to determine which zone is represented, for 

 here truly Arctic species are associated with those of lower altitudes. 

 On rock slides and on exposed summits the flora is decidedly different, 

 and there is no doubt that it is purely Arctic. Just as soon as one 

 leaves the meadows and begins to climb a rock slide, an abrupt 

 change in the flora is apparent, yet it is hardly possible to restrict the 

 Arctic-Alpine Zone to these slides and to the exposed summits. 



There are no trees in the zone, of course, but there are dwarfed 

 shrubs, especially low willows, which frequently form dense bushy 

 masses of considerable extent. At Cracker and Iceberg lakes wil- 

 lows are particularly abundant. Most of them are shrubs 30 to 60 

 cm. in height, but there are also smaller species, some of which creep 

 closely along the ground. Scrub birch sometimes grows on high slopes, 

 also bush cinquefoil; and the heathers grow here as well as in the 

 Hudsonian Zone. Two species of Dryas are common, but in spite of 

 their woody -stems they resemble herbs much more than shrubs. 



