348 



Rydberg: Phytogeographical notes 



Herbs 



\Eriophorum Scheucheri 

 t " alpinum 



\Jii7icoides arcticum 

 t ' ' arcuatum 

 ^Orchis rotimdifolia 



^Arenaria norvegica 

 \Drosera longifolia 

 \Condrosea Aizoon 

 \Leptasea tricuspidata 



II 



I. Species nearly equally distributed in the Rockies and 



THE Pacific mountains 



There are many species which seem equally at home both in the 

 Rocky Mountains, the Sierra Nevada and the Cascade Mountains- 

 The larger part of these are more or less xerophytic plants growing 

 in the drier part of the subarctic zone, especially on southern 

 exposures. Nearly all of the plants listed below are also equally 

 distributed in the Montane and the Subalpine Zones. To these 

 belong four of the conifers, Pseudotsuga rmicronata, Pinus Murray- 

 ana, P. flexilis and P. albicaulis. Of these the last mentioned 

 is the only one which is not better represented in the Montane 

 Zone. Its distribution is also more extensive in the Pacific moun- 

 tains, and it is not found in the Southern Rockies. It has therefore 

 been placed among the immigrants, though its original home might 

 be the Northern Rockies. Pseudotsuga mucronata is also found in the 

 mountains of northern Mexico. All extend north in the Rockies to 

 about latitude 55 degrees, except Pinus Murrayana, which grows 

 much further north in the Yukon Valley, at latitude 65 degrees. 



Pseudotsuga mucronata 

 Pinus Murrayana 



Salix glaucops 

 Ribes montigenum 

 Pachystima myrsinites 

 Phyllodoce empetriformis 



Trees 



Pinus flexilis 



Shrubs 



Ledum glandulosum 

 Kalmia microphylla 

 Gaultheria humifusa 



