460 Rydberg: Phytogeographical notes 



Alpine lake formation 

 Alpine mat formation 

 Alpine rock-field formation 



While my observations at other places in the Rockies agree 

 essentially in most respects with Professor Clements' arrangement, 

 it cannot be applied without modification to all localities in the 

 Rockies, not even to all in Colorado. When the whole of the 

 southern Rockies is considered, some modifications must be made, 

 and if the alpine region of the northern Rockies is included, still 

 more adjustment is needed. Here there are found formations of 

 ericaceous plants, consisting of undershrubs, if not, as in the Alps, 

 of shrubs. Perhaps I lay too much stress upon the moisture in 

 the ground and soil, and therefore would be inclined to subdivide 

 Professor Clements' alpine meadow formation. 



The Rocky Mountains have received their name from the 

 numerous loose rocks that cover their tops and sides. In naming 

 plants from the Rocky Mountains, the specific name usually 

 used has been scopulorum. This is really a misnomer, for it is 

 not from scopiilum (a projecting cliff) but from saxum (the loose 

 rock), that the Rockies were named. W 7 hen the mountain dis- 

 integrates it breaks up into large blocks. These in the Rockies 

 cover large fields, or, as they are mostly on the slopes, they are 

 often more or less in motion and are usually known as "rock- 

 slides." The first form of vegetation which appears on a newly 

 formed rock-slide is, of course, lichens. Whenever there has been 

 deposited a little humus between the rocks a few flowering plants 

 appear, mostly perennials, with strong root systems or with strong 

 rhizomes. Thus arises the first formation, the 



Rock-slide formation 



If the rocks disintegrate still more, they become broken up into 

 smaller pieces and more humus is added and there arises a gravel- 

 field. If the disintegrated portion is rather thin, as it usually is 

 on the top of the peaks and along the ridges, the formation is a 

 xerophytic one, as little of the water from the melting snow is 

 retained. So we have our second formation, which corresponds 

 to Dr. Clements' alpine mat formation. This may be called the 



