characterized by the Artemisia tridentata/Agropyron spicatura 

 type. 



Other Studies. — This type has not previously been reported in 

 Montana but has been reported in Colorado, Idaho, Oregon, and 

 Washington (Bourgeron and Engelking 1991) . 



2 1 . Phalaris arundinacea Type 



(PHAARU; reed canarygrass; G4 S4) 



Vegetation. — Phalaris arundinacea dominates (often with a 

 total canopy cover of 100%) . The undergrowth is typically 

 very depauperate due to the intense competition with P. 

 arundinacea . Poa palustris may be well represented and 

 Cirsium arvense and Mentha arvensis are often common. The 

 total cover of the few additional species seldom exceeds 1%. 



Physical Setting. --This type occurs on gravelly alluvial 

 parent materials on flat flood plains in wide valley bottoms 

 at elevations around 5000 feet. Litter and soil cover equals 

 or exceeds 30% and 20% of the ground surface, respectively. 

 The soil surface is generally stable with no evidence of 

 accelerated erosion. 



Soils are often Fluvaquents or Fluvents, are very deep 

 with loamy sand to loam textures, medium available water 

 holding capacity, and are non-calcareous. Coarse fragment 

 contents vary from none to gravelly. 



Adjacent Communities. --Adjacent wetter sites often feature 

 open water while adjacent drier riparian communities include 

 the Populus trichocarpa/Cornus stolonifera type and a wide 

 variety of other riparian types. 



Other Studies. — This type has been described in Montana by 

 Hansen et al. (1991) . 



Special Status Plant Observations 



The eight TES plant species observed within the study plots, 

 the plot numbers in which they were found, and the global and state 

 rarity rankings for these species are presented in Table 1. Pre- 

 liminary verification of the Lesquerella paysonii specimens by Dr. 

 Reed Rollins of the Harvard University Herbaria suggests these 

 specimens may be L_^ prostrata (also a SI species) . Dr. Rollins 

 indicated in a December 11, 1991 letter that he will resolve this 

 identification problem as soon as possible. 



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