24 THE JOURNAL OF INDIAN BOTANY. 



Nor are strand-plants however ordinary xerophytic psammo- 

 phytes. Psammophytes are as a rule deep rooted, and draw on 

 deep-lying water for their supply. These strand -plants do not. 

 Their roots do not grow deep, and in Spinifex at least the root- 

 hairs are, as we have seen, close to the surface and depend appa- 

 rently on water close to the surface of the ground. This water 

 would, we have seen, he fresh. A certain amount of salt must be 

 blown in from the sea as spray and this would be leached though 

 the surface layers by the next shower of rain down to a certain depth. 

 Perhaps this accounts for the formation of an exodermis and the 

 absence of root-hairs on the lower roots of Spinifex squarrosus. 



Finally there is another condition different from that of either 

 a desert or sand-field. The air blown across from the sea is damp. 

 It is never dry by the sea, except when the land breeze blows strongly 

 it is damp close to the water. The strand-plants therefore are 

 xerophytic in the sense of having to depend on very little fresh water, 

 but in regard to the water lost by evaporation from the leaves have 

 much less to fear than even mesophytic inland plants. They are 

 surrounded by air as damp as that round a lake. They are not 

 halophytes. They are not xerophytes in the ordinary sense, but 

 subject to the peculiar condition of a shortage of water available to the 

 roots, yet without liability to extensive loss from the leaves. Perhaps 

 their chief physiological characteristic is therefore the ability to carry 

 on metabolism with a minimum of water passing through the system. 



As regards the xerophytism of strand-plants, Kearney (5) 

 came to similar conclusion after analysis of the salt-content of the 

 soil. He found that seashore sand contains less salt than some 

 cultivated soils. Kearney insists on the xerophytic character of 

 plants as being due to dry winds and dry sand. But a distinctly 

 moist air seems in Madras to be the rule near the sea. 



Literature Cited. 



(1) Olssoh-Seffer. New Pbytologist VIII (1909), p. 38. 



(2) Price, B. New Phytologist X (1911), p. 328 et seq. 



(3) Schimper, A. F. W. S.B.K. Preuss, Akad, Wiss., 1890, 



pp. 1045-1062 extr. in J. R.M.S. 

 1891, p. 214. 

 Plant Geography, p. 184. 



(4) Warming E. (Ecology— Eng. Ed. (1909), p. 227. 



(5) Kearney. T. H. Bot. Gazette, XXXVII (1904), p. 424. 



