Rydberg: Phytogeographical notes 461 



Mountain crest formation 



If the gravel field or rock field is situated on the sloping moun- 

 tain side, either under a snowdrift or along the course of the 

 drainage, in other words where the moisture is greater and where 

 more humus has a chance to gather, we have our third formation, 

 which I shall call in lack of a better word the 



Mountain seep formation 



This was included by Clements in the mountain meadow. 

 While the mountain seeps have many plants in common with the 

 meadows, there are found others wholly characteristic of these 

 seeps, as for instance certain species of the saxifrage family and 

 several willows. Where the ground is less sloping and the humus 

 has had chance to gather still more, there is found the 



Alpine meadow formation 



If the drainage is imperfect and the water becomes stagnant, 

 the next formation occurs, the 



Alpine bog formation 

 or if deeper, the 



Alpine lake or pond formation 



To this can also be added special formations. There are certain 

 plants that grow only in the crevices of exposed cliffs. Hence, the 



Cliff formation 

 Another is found only below and around the melting snowdrifts, 



the 



Snow-drift formation 



Of these the rock-slides and mountain crest formations are 

 decidedly xerophytic; the cliff formation mostly mesophytic but 

 often xerophytic, the meadow and mountain seep formations 

 mesophytic or the latter usually hydrophytic; of course, the bog 

 and lake formations are hydrophytic. 



i. Alpine mountain crests 

 I shall begin with this formation, as ic is perhaps the most 

 characteristic of the alpine formations. The plants are nearly all 



