ALKALI-INDICATING PLANTS 63 



others. On the other hand, shallow-rooted plants which 

 cannot endure alkali may grow luxuriantly on land which 

 contains alkali below the depth to which its roots feed 

 but so near to the surface that when farming is attempted 

 the land may soon be ruined. The latter condition is 

 represented by the Bear River Valley, Utah, where sage 

 brush, rabbit brush, and salt grass are growing on land 

 practically free from alkali in the upper foot or so, but the 

 soil to a depth of six feet contains from 6000 to 30,000 parts 

 per million of salts, mostly sodium chloride. This salt is 

 quickly concentrated near the surface when irrigation is 

 practiced, making farming impossible. 



Alkali-indicating Plants. Some of the characteristic 

 plants of the western part of the United States which 

 should, when present as a luxuriant growth upon- the land, 

 be regarded as indicating distinctly alkali soil, or soil 

 which should be looked upon with suspicion until chemical 

 analyses of it have been made, are given below. 



Well-defined alkali-indicating plants 



Inkweed, or saltwort (Suaeda spp.) 



Tussock grass, or purple top (Sporobolus airoides). Torr. 



Bushy samphire, or Kern greasewood (Allenrolfea occidentals) (S. Wats.). 



O. Ktze. 



Dwarf samphire (Salicornia spp.) 

 Greasewood (Sarcobatus vermiculatus) 



Alkali-heath (Frankenia grandifolia campenstris) . A. Gray 

 Spike weed (Hemizania pungens) 



Little rabbit brush (bushy goldenrod) (Isocoma veneta) H. R. K. (A. Gray) 

 Arrow or irrigation weed (Pluchea serviced) (Nutt.). Coville. (Sometimes 



Pluchea borealis) 



Salt-bush or shadscale (Atriplex confertifolia, etc.) 

 Kochia or white sage (Kochia vestita) 

 Salt-grass (Distichlis spicata). Greene 

 Cressa (Cressa cretica truxillensis). Choisy 

 Rabbit brush (rayless or false goldenrod) (Chrysothamnns spp.) 



