74 NATIVE VEGETATION AS AN INDICATOR 



weed (Pleuchea borealis), a composite with a brush-like 

 head supported on a stem 4 to 8 feet high which tolerates 

 a limited quantity of alkali on a porous, deep, well-drained 

 soil. Plants other than those discussed above are char- 

 acteristic of alkali lands in their respective districts, but 

 sufficient data are not at hand to determine their exact 

 reliability as to alkali resistance. Many other plants 



FIG. 13. PLANTS GROWING AT THE TOP OF SAND DUNES, THE ONLY 

 PLACE WHERE THE ALKALI is NOT TOO STRONG FOR PLANT GROWTH. 



grow upon alkali land during the wet season when the soil 

 solution is dilute, but none of them can.be classified as 

 distinctive in determining soil alkali conditions. 



Description of Alkali-indicating Plants. Allenrolfea 

 occidentalis (Watson) Kinitze. Bushy samphire or kern 

 greasewood is a shrubby evergreen bush i to 4 feet high 

 with numerous cylindrical, jointed, fleshy, practically leaf- 

 less alternating branches. The leaves are triangular or 

 scale-like in shape. It has a large taproot and but few 

 lateral roots. Generally found in low-lying moist lands 

 from the 40 th parallel southward, the northern plants 



