OF THE HAWAIIAN ARCHIPELAGO ~ 491 
The importance of the evaporation factor, particularly in the 
early stages of an association, is admirably emphasized by Tran- 
seau (’08, p. 230), who states: 
The greatest decrease in the demands for transpiration on the part of seedlings 
takes place during the first stages. This greatly aids in accounting for the well-known 
called to the importance of pioneers as shade-producers, while their effectiveness in 
reducing transpiration has been underestimated. 
On the Hawaiian beaches a combination of factors—warmth, 
brilliant insolation, and exposure to powerful and rarely inter- 
mittent winds—tend to augment transpiration, and make of it an 
influence of great potency in retarding certain plants and com- 
pletely inhibiting many others. 
HAWAIIAN TIDES AS RELATED TO THE LITTORAL 
On all oceanic coasts and embayments the tides exert an in- 
fluence of greater or less power in determining the seaward limits 
of the land vegetation, and the landward extensions of the marine 
flora. In regions where the tidal range is great the effect upon 
the shore-line vegetation is proportionately augmented; in regions 
where the range is slight, its influence is small or negligible. The 
Hawaiian Archipelago comes under the latter class. 
The greatest tidal contrasts in the Hawaiian Islands are due to 
coastal topography, i. e., sea-cliffs contrasted with mud-flats that 
lie only a few inches above low tide. At the foot of the sea-cliffs 
which rise directly from the water is a tidal (and wave-splash) 
zone of two or three feet. This zone is conspicuously marked by 
the coralline algae, which form a reddish-purple or lavender band. 
If conditions for land-plants are favorable, they may occur only a 
few feet above this zone, within reach of the salt spray, and from 
a distance appear to rise from. the sea itself. Plant-clad cliffs of 
this character also occur in many of the South Pacific islands. 
The mud-flats, however, present broad, rocky, mud-covered 
platforms, a few rods to a half-mile in width, almost free from sea- 
water at low tide, but covered at high tide with six to twenty-four 
inches of water. The land vegetation is restricted to the shore- 
ward limits of these flats. The absence of the land-building 
halophytes—Rhizophora, Brugutera, Ceriops, Kandelia, etc.— 
makes invasion very slow. 
