ON THE WATER RELATIONS OF THE COCONUT PALM 
(COCOS NUCIFERA). 
By Epwin BINGHAM COPELAND. 
(From the Botanical Section of the Biological Laboratory, Bureau of Science.) 
The work on Cocos nucifera (coconut), the result of which is reported 
below, was performed at the Government farm at San Ramon, near 
Zamboanga. Its purpose was to acquire as thorough a knowledge of the 
physiology of this palm as the field conditions would permit, with the 
especial hope that the results would be available for improving existing 
methods of the plant’s cultivation. 
Because of the remoteness of the place of work from any library or base 
of supplies, the simplicity of apparatus which for the greater part is used 
in investigating all phases of a plant’s transpiration, the writer’s famil- 
iarity with this particular field, obtained in the preparation of earlier 
papers, and because of the very great practical importance of understand- 
ing this phase of the physiology of any plant important in agriculture, 
the work was principally focused on the water relations of the coconut. 
At the same time other phases of the tree’s activity were not neglected ; 
and, in cases where it seemed worth while, notes not bearing on the main 
- subject are included in this paper. The value of artificial or natural 
fertilizers was not considered, because this question is more in the domain 
of the agriculturalist. 
The divisions of the main subject are treated in the following order: 
The root—its structure and growth, and the absorption of water; the 
leaf—its structure, the activity of the stomata, and the transpiration ; 
with final conclusions as to the fitness of the plant for its characteristic 
habitat and suggestions as to its most advantageous cultivation. 
THE ROOT. 
The roots of Cocos nucifera have the two typical root functions—the 
anchoring of the tree and the absorption of the water and mineral food 
necessary for its maintenance and growth. In the absence of a taproot, 
or of any great roots the hold of which in the ground can maintain the 
rigidity of the trunk, the mechanical problem of the firm anchorage of the 
latter finds a solution essentially different from that which we are 
accustomed to encounter in the case of dicotyledonous trees. The base of 
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