Rydberg: Phytogeographical notes 635 



I. Lakes, Ponds and Swamps 

 The water grasses are not many. Catahrosa aquatica is mostly 

 confined to slow running brooks, Phragmites Phragmites, Panicu- 

 laria americana and P. boreaUs are found in lakes and ponds 

 mostly near the shore; so also are Phalaris amndinacea, Agrostis 

 asperifoHa, Beckmannia erucaeformis, and Calamagrostis Langs- 

 dorfii, but these prefer the bogs rather than the deeper water. 

 The following belong to this formation : 



Phalaris amndinacea *Phragmites Phragmites 



* Calamagrostis hyperborea *Paniciilaria america?ia 



Agrostis asperifolia J " nervata 



*Beckmannia erucaeformis f " pauciflora 



X\Catabrosa aquatica t " borealis 



The following is restricted to the Northern Rockies: 

 Panicularia elata 



2. Meadows 



As in the Subalpine Zone the wet meadows are situated in the 

 more open valleys, but they are here of greater extent, as the 

 grade of the water courses is not so steep as in the higher regions. 

 Many of the grasses are the same as those of the subalpine mead- 

 ows and even some of the alpine species, such as Poa alpina and 

 Phleum alpinum, are occasionally found along the water courses, 

 where the ground is kept cool by the ice water from the mountains. 

 Still more species are common to this and the valleys of the Foot- 

 hills and the Great Plains. The genera of Aveneae, such as De- 

 schampsia, Trisetum and Graphephorum, become more sparing, and 

 thoseof Agrostideae, such as ^o;ro5/w, Muhlenbergia and Calama- 

 grostis, more common. The tribe Hordeae, rarely represented in the 

 subalpine meadow, becomes also more frequent, especially the 

 genus Hordeum and the stoloniferous species of Agropyron. It 

 is scarcely worth while to indicate the principal species, for in 

 one meadow there might be one species predominant, in another 

 there might be another species. In the Northern Rockies the 

 predominant species in many places are Alopecurus occidentalis, 

 Agrostis alba, Phalaris amndinacea, or Festuca vallicola, but in 

 the Southern Rockies this is rarely if ever the case. Here the 

 species of Poa are usually predominant. The following grasses 

 inhabit the montane meadows: 



