STANDLEY FLORA OF GLACIER PARK. 241 



The Transition Zone is moderately well differentiated from the 

 Canadian, but there are certain complications. The prairie, of course, 

 is purely Transition, but in the foothills and low valleys it is often 

 impossible to tell whether a given area is more typically Transition or 

 Canadian. The lower open slopes are usually without any Canadian 

 intrusion, but on the higher rocky slopes, like those of Altyn Peak, 

 plants of the two zones are intermingled. In fact, about snow banks 

 upon such slopes Arctic-Alpine plants grow in close proximity with 

 Transition ones. Sometimes patches of apparently Transition vege- 

 tation occur at high altitudes, as at Cracker Lake. On the other hand, 

 Canadian vegetation, characterized by a heavy, growth of trees, often 

 extends to low altitudes, especially along streams. 



The species of the Transition Zone are mostly ones which are char- 

 acteristic of wide areas of the Great Plains. Many of them extend 

 eastward to Minnesota and southward to Texas. The species of this 

 zone are most easily studied at the east entrance, at St. Mary, and 

 just below Lake McDermott. 



The most interesting portion of the zone, as represented in the 

 Glacier Park region, is found on the prairie about the east entrance. 

 The plains here are broken by deep canyons, with precipitous banks 

 composed of crumbling shale. Several of these canyons are within a 

 few minutes' walk of the Glacier Park Hotel, but from a short distance 

 one would never guess their existence, for the landscape appears to 

 consist of a continuous expanse of rolling prairie On the shale 

 slopes anumber of species are found which are rare or absent elsewhere. 

 Of greater interest, however, are the small ponds and marshy spots 

 scattered all over the prarie. In 1919 all these places were quite 

 dry, but in a year of moderate rainfall they must be full of water or at 

 least wet throughout the season. Umbach collected here a number 

 of water plants not found by the writer; in 1919 there was no water 

 in which they might grow. But in such an abnormally dry season 

 these spots supported a large number of plants found nowhere else, 

 like Typha, Sagittaria, Alisma, Rumex maritimus, Polygonum muhl- 

 enhergii, PotentiUa anserina, Taraxia, BoisduvaUia, Hippuris, Gen- 

 tiana affinis, Navarretia, AUocarya, and Orthocarpus. In many of 

 these depressions the soil is strongly alkaline, and there are found a 

 a few halophilous plants, such as DisticJilis spicata, Dondia depressa, 

 Atriplex Jiastata, dhenopodium humile, and Halerpestes cymhalaria. 



CANADIAN ZONE. 



The Canadian Zone covers by far the largest portion of the park, 

 for it includes all the timbered portion except a narrow belt just 

 below timber line (see pis. 37, 38, B) . It extends from practically the 

 base of the mountains (1,440 meters on the east slope and 950 meters 

 on the west slope) up to an elevation of 1,800 to 2,100 meters, accord- 



