BIOLOGICAL RELATIONS OF DESERT SHRUBS. 
II. ABSORPTION OF WATER BY LEAVES. 
V. M. SPALDING. 
DurInc a study of certain shrubs growing in the vicinity of the 
Desert Botanical Laboratory near Tucson, Arizona, it has been 
found that the leaves of some of them absorb water, while those of 
others do not. Although leaf absorption is treated by leading physi- 
ologists as a matter of indifference, or at any rate of secondary 
importance, it has seemed worth while to inquire whether differences 
of habit in this particular, on the part of these desert plants, may 
not be correlated with other characteristic peculiarities; if so, even if 
the fact should turn out to be of small importance physiologically, 
it may be significant from a biological point of view. 
Our knowledge of leaf absorption as yet is fragmentary and 
uncertain. For the general subject it is quite unnecessary to cite 
the voluminous and contradictory literature. DANDENO’ has given 
a useful historical résumé, reference to which and to paragraphs 
in BURGERSTEIN’S more recent work? is sufficient for the present 
purpose. In regard to various highly modified plants, however, 
the case is quite different. ScHurmper has made such detailed 
observations of certain epiphytes as to leave no doubt that they - 
normally absorb large quantities of water through their aerial parts, 
and that this is a distinct physiological advantage, or even neces- 
sity. In view also of investigations cited by BURGENSTEIN it becomes 
necessary to accept the fact of leaf absorption in the case of various 
other plants. 
As for the plants of arid regions, the evidence has been less con- 
clusive than could be wished. VotkENs, in his classical work, 
describes various special structures by means of which, presumably, 
many of the plants of the Egyptian-Arabian desert take up dew 
* DANDENO, J. B. An investigation into the effects of water and aqueous solutions 
of some of the common inorganic substances on foliage leaves. Trans. Can. Inst. 
75230. 1908. 
2 BURGERSTEIN, A., Die Transpiration der Pflanzen. 1904. 
Botanical Gazette, vol. 41] [262 
