70 NATIVE VEGETATION AS AN INDICATOR 



contain comparatively small quantities of alkali, and 

 " where this bush is found growing uniformly over an area 

 to the exclusion of the most resistant alkali indicators, 

 the alkali is found below the surface from i to 3 feet in a 

 free sand or sandy loam soil. This " land yields crops " of 

 alfalfa and grain or orchards and can be kept free from 

 injurious quantities of alkali by proper methods of irriga- 

 tion and drainage." 



Cressa (Cressa cretica tmxillensis) is a perennial herb 

 with a woody base from which many leafy branches ex- 

 tend. The leaves are almost sessile and are characterized 

 by their silky, villous, and hairy nature. Cressa is a com- 

 mon sea-coast plant in many of the arid parts of the world. 

 In the United States it is found along the Texas coast 

 and scattered throughout California, extending at least 

 to the Arizona line. Alkali-heath has been found growing 

 with a higher total salt content than Cressa, but Cressa is 

 a surer indicator of irreclaimable alkali land because the 

 lower limit in which it grows is much higher. Although 

 sulphates predominate in Cressa soil, it will be noticed 

 that it does well with chlorides in quantities dangerous 

 to ordinary crops. 



Salt-bush, or Shadscale (A triplex spp.), is of two types - 

 the perennial, which is generally bushy or shrubby, and 

 the type that occurs as an annual weed. The leaves are 

 usually alternate, simple, and often silvery, scurfy, or 

 having an ashen-gray color, the bush type often being 

 mistaken for sagebrush. The bush belongs to the same 

 family as the beet and it can readily be detected by its 

 beet-like seeds. A number of the A triplex species grow 

 in soil which contains little or no alkali, but the moisture 

 conditions are generally unfavorable on any soil which 

 has a vigorous growth of them, and most of the common 



