324 SOIL TYPES [chap. 



The salt marshes possess a characteristic vegeta- 

 tion of what are termed halophytes, plants capable 

 of resisting a considerable quantity of salt in the 

 medium in which they grow. Among cultivated 

 plants, mangolds, asparagus, and crucifers like cabbage 

 are most tolerant of salt, and the two former are true 

 halophytes. 



Many halophytes live by acting as xerophytes, and 

 taking very little water up ; they are also able to 

 store away in their tissues quantities of saline matter 

 which would be toxic to the majority of plants. The 

 ash of Armeria maritima shows 12 to 15 per cent, of 

 chlorine in the ash ; in Aster tripolium the proportion 

 rises to over 40 per cent, in the ash of the leaves, and 

 to 50 per cent, in that of the stem ; yet although the 

 plants habitually contain these large amounts of salt, 

 they will grow perfectly well in ordinary soil where 

 they can get but little. 



The Australian salt-bush [Atriplex semibaccatum) 

 which has already been mentioned as tolerant of a 

 large amount of alkali in the soil, also removes much 

 soluble matter the dry plant containing as much as 

 20 per cent, of ash, so that the salt content of 

 the soil may be materially reduced by cropping with 

 this plant. The halophytes seen in the salt marshes 

 of this country consist of various species of Atriplex j 

 Beta (the source of the cultivated beets and man- 

 golds), and other Chenopodiaceae, Statice armeria, 

 Aster tripolium, Frankenia, and a number of crucifer- 

 ous plants like Crambe, and Cakile, with umbellifers 

 like Crithmum. Some plants show a great dislike to 

 salt, even in small proportion, e.g., the Rosaceae, 

 Orchidaceae, and the Ericaceae. 



