630 Rydberg: Phytogeographical notes 



drainage are both good and where there is no special exposure 

 either to wind or snow are occupied by grasses and not by forest. 

 In such cases it is harder to point out the causes of the conditions. 

 In some cases the forests have been destroyed by fires, and the 

 grasses have gained possession of the ground before a reforesta- 

 tion had taken place. 



A. SUBALPINE ZONE 



The grasslands of the Subalpine Zone resemble much those of 

 the Alpine Zone, which has been treated in a previous article. They 

 are, however, of comparatively less extent, only covering larger 

 areas in the more open valleys, where too much snow lodged, and 

 along the wind-swept "hog-backs." The former are practically a 

 continuation of the alpine meadows, the latter of the mountain 

 crests. The grasses are mostly the same with some additions 

 from the Montane Zone below. The grasses confined to the 

 Subalpine Zone only are indeed very few. 



Species in the following lists marked with an asterisk (*) are 

 restricted to the lower parts of the zone; those marked with a 

 dagger (f) to the upper part. 



I. Lakes, Ponds, Brooks and Swamps 



Lakes or ponds are very rare in the Subalpine Zone ; they are 

 mostly situated in amphitheaters immediately under the snow fields 

 and are usually filled with ice until late in the spring. They are 

 almost void of higher vegetation, which is limited to a few species 

 of Sparganium and Potamogeton. There are, as a rule, no grasses. 

 The only aquatic grass in the upper part of the Zone is Catabrosa 

 aqiiatica, which is usually confined to the mountain brooks in places 

 where the current is less swift. In the lower part of the Zone is 

 added to this Panicularia pauciflora, growing in willow bogs. 

 Th ecommon water grasses of the lower mountain regions and the 

 Great Plains are wanting: viz. Phragmites, Spartina, Calamagrostis^ 

 Panicularia americana, and Phalaris. 



2. Meadows 



The wet meadows are confined to the lower and moister parts 

 of the open valleys. In the upper part of the Zone they are 

 practically identical with the Alpine meadow-laiids ; in the lower 



