KEARNEY: PLANT LIFE OX SALINE SOILS 115 



genera of Chonopodiaceae and in the tamarisks, the assimilat- 

 ing tissue is located mainly in the stems, the leaves being mere 

 scale-like vestiges. The mangroves are a striking exception, 

 possessing a heavy crown of broad leaves. 



Thickness of the leaves and stems characterizes most halo- 

 phytes, aside from the grasses and grass-like plants. LeSage^^ 

 compared numerous maritime species with the most nearly re- 

 lated inland forms and found that in the great majority of cases 

 the former had the thicker leaves. In some species the thick- 

 ening results merely from an increase in size of cells or in number 

 of layers of the chlorophyll tissue, but many halophytes possess 

 also a specialized water storage tissue of thin-walled cells, con- 

 taining few or no chloroplasts. 



The degree of succulence is closely associated with the salinity 

 of the medium. Several investigators have reported that non- 

 halophj'tic species, when watered with salt solutions, show an 

 increase in the thickness of the leaf. Conversely, halophytes, 

 when grown in an ordinarj' garden soil with fresh water irri- 

 gation, often develop thinner leaves and stems than in their 

 natural habitat. Batalin^^ found that even Salicornia re- 

 sponded in this manner. Holtermann^^ obtained a marked in- 

 crease in the thickness of the water storage tissue of man- 

 groves by watering the plants with a sodium chloride solution 

 of about twice the concentration of sea-water. On the other 

 hand, irrigation with fresh water resulted in the development 

 of much thinner leaves than were observed in the normal habitat. 



Casu^^ has pointed out that succulent halophytes occur in 

 nature only where the soil has a high water content as well as 

 a high salt content. It is otherwise with the succulent xero- 

 phytes, such as Cactaceae, which prefer soils that are normally 



" P. Lesage. Recherches experimentales sur les ynodifications des feuilles chez 

 les plantes maritimes. Rev. Gen. Bot. 2: 54, 106, 163. 1890. 



" A. Batalin. Die Wirkung des Chlomatriums auf die Entwickelung von 

 Salicornia herbacea. Bull. Congr. Internat. Bot. Hort., 1884, p. 219. St. 

 P^tersb. 1885. 



15 C. HoLTERMAXx. Der Einfluss .des Klimas auf den Bau der Pflanzengewebe. 

 Berlin, 1907. 



" A. Casu. Contribuzione alio studio della flora delle saline di Cagliari. Ann. 



di Bot. 2: 403. 1905. 



t 



