OF THE HAWAIIAN ARCHIPELAGO 489 
have been introduced into the islands within historic times. The 
ravages of wild live-stock, such as cattle, goats, sheep, and swine; 
the clearing of the lowlands for agricultural and other purposes; 
the building of roads; the large quantities of firewood which were 
drawn from the nearest and most easily available sources; the 
introduction of a great variety of pernicious foreign weeds—all 
of these factors have contributed largely to the depletion of the 
lowland and littoral floras, and have given them an aspect of 
meagerness that they probably did not possess in their primitive 
state. Man and his domestic animals have been much more potent 
limiting factors than has been precipitation. 
WIND ACTION 
The wind is a powerful agency in its direct mechanical effects 
upon beach vegetation. Many strand plants have forms that 
are more or less protective, i. e., prostrate, creeping, rosette, or 
hemispherical aerial bodies. ‘Plants of upright habit are per- 
manently deflected and shaped by the wind; the windward branches 
are stunted and warped, and growth takes place chiefly on the lee- 
ward side of the plant. Seaside plants of Acacia farnensiana, 
Prosopis juliflora, Santalum Freycinetianum var. littorale, Calophyl- 
lum inophyllum, and Kadua littorale commonly illustrate this 
condition. These wind-beaten plants are invariably dwarfed. 
The mechanical effect of the wind is greatly augmented on 
those coasts upon which it is able to pick up quantities of beach 
sand. At storm times, in such regions, the wind becomes a veri- 
table sand-blast. The evidences of this sand-blast action, upon 
the trunks of both living and dead trees, and upon the local topog- 
raphy itself, are familiar to all who have travelled along a windy 
coast. The fantastic sculpturing of the seaward slopes of tufa in 
the Koko Head region, and at Mokapu Peninsula, admirably 
illustrate this sand-blast work. The herbaceous vegetation on 
these slopes is either prostrate or rosette, ©. g., Sesuvium Portula- 
castrum, Argyreia tiliaefolia, Boerhaavia diffusa; or tough and wiry, 
e. g., Sporobolus virginicus, Fimbristylis pycnocephala. 
On the Hawaiian littoral the wind is not as important an 
ecologic agent as in such a region as the Lake Michigan sand dunes. 
Here, according to Cowles (’99, p. 108), it ‘‘is the chief destroyer 
