KEARNEY: PLANT LIFE ON SALINE SOILS 121 



istic of soils rich in nitrogen also possess this power of selective 

 absorption. Individuals of these species were found to give a 

 strong reaction for nitrates, even when growing on soils of low 

 nitrogen content. 



The quantity of water-soluble salts taken up by halophytes 

 is often considerable. Cameron" found that in a sample of 

 greasewood (Sarcobatus) salts of sodium constituted about 20 

 per cent of the total dry weight of the leaves, x4.ll of the sodium 

 chloride present was apparently free in the cell-sap and could be 

 recovered by leaching the dry material with water, as Deherain^^ 

 had previously ascertained to be the case with Salsola Kali. 

 Paris, on the other hand, states that in Atriplex Halimus, the re- 

 sults of freezing-point determinations indicated that, of the total 

 chlorine found in the ash, only about half was free in the cell sap. 



In view of the injurious effects of concentrated solutions of 

 sodium salts upon ordinary plants, the question arises, how are 

 halophytes able to adjust themselves to such extreme salinity of 

 their cell-sap? A strong development of water tissue, the cells 

 of which contain few or no chloroplasts, is, as we have seen, 

 characteristic of many salt plants. The plausible suggestion 

 has been made that much of the salt taken up by such plants is 

 stored in this tissue, rather than in the green assimilating cells, 

 although apparently no direct evidence of such segregation has 

 been obtained. 



Many halophytic species are able to check the accumulation 

 of salt in their tissues by excreting it, in solution, upon the sur- 

 face of their leaves and stems. This phenomenon is not con- 

 fined to plants that possess specialized excretory organs. In 

 the case of grasses hke Spartina and DistichUs excretion is sup- 

 posed to take place through the stomata.*^ 



The best known cases of salt excretion are found in the 

 Plumbaginaceae, Frankeniaceae, and Tamaricaceae. The mem- 

 bers of these famiUes are characterized by the possession of 



" F. K. Camerox. U. S. Dept. Agr. Rep. 71: 64-66. 1902. 



3* P. Deherain. Sur l' assimilation cles substances minerales par les plantes. 

 Ann. Sci. Nat. VI. Bot. 6: 366. 1878. 



^^ A. B. Klugh. Excretion of sodium chloride by Spartina glabra alterniflora. 

 Rhodora 11: 2.37. 1909. 



