SECTION VII 



CLASS V. HALOPHYTES. FORMATIONS ON 



SALINE SOIL 



CHAPTER LIV. INTRODUCTORY GENERAL REMARKS ON 



HALOPHYTES 



Saline soil occurs upon the Earth in many places, namely, along the 

 shores of all oceans and saline lakes, by salt-springs which occur in many 

 spots (for instance in Germany),^ on steppes where salts contained in the 

 soil cannot be washed out or are carried down into depressions by floods 

 of ram. According to Bunge there are nine of such great salt tracts, of 

 which each has its own floristic peculiarities : these tracts are identical 

 with the steppe-regions the Australian lowland, Pampas, central parts 

 of North America, western and eastern Mediterranean regions, South 

 Africa, regions of the Red and Caspian Seas, and Central Asia. The 

 salts concerned are especially common salt, gypsum, and magnesium 

 salts. 



Wherever the soil is saline there appears a special type of vegetation, 

 which is produced by a few definite families, and is composed of morpho- 

 logically and anatomically peculiar forms. A certain amount of soluble 

 salts must be present before halophytic vegetation is called into existence ; 

 but the nature of the salts seems to be a matter of indifference ; at least 

 the vegetation agrees in all essentials - in the following situations : saline 

 spots in Hungary where the salt is sodic carbonate, in Transylvania 

 where it is sodic chloride, near Budapest at the bitter salt-springs, where 

 the salts are sodic and magnesic sulphates. But the deleterious action 

 of various salts differs widely.-^ 



Halophytic vegetation is extremely hardy in relation to climate, 

 for instance, in regard to altitude above the sea-level ; in all parts of the 

 world, under all climates, at all altitudes, where it occurs it bears the same 

 stamp. Certain species have a wide distribution ; for instance, this is 

 true of Salsola Kali (in many places this is not a halophyte) and of Glauxj 

 maritima, which occur not only on the coasts of north-western Europe, 

 even on the rainy shores of Norway, but also on the salt-steppes of Tibet ;] 

 while Salsola in North America has become a pestilent weed in cornfields. 



Two other features common to halophytic communities are thej 

 exceeding poverty of the flora and the very open nature of the vegetation. 

 The action of salts in excluding plants has already been explained on I 

 p. 67. But it must be added that the degree of ease with which [ 

 soil dries plays a part ; for when the soil dries readily a small amount j 



^ See Ascherson, 1859 ; Petry, 1889. * Bernatsky, 1905. 



^ Kearney and Cameron, 1902. 



