486 MacCauGHEY: THE STRAND FLORA 
3. Not subjected to shadows: as for 2. 
4. Heat reflected by neighboring objects: e. g., Mana-dune strand, 
Koko Head tufa cliff coast, Mokapu. 
5. Composed of dark materials which absorb and retain heat: 
lava beaches of Hawaii, Maui, and parts of Oahu and 
Kauai. 
6. Texture unfavorable for rapid evaporation of moisture: mud 
beaches and tufa cliff beaches, e. g., Pearl Harbor Inlet and 
Mokapu. 
7- Arid or semiarid: not receiving the cooling effects of rain, 
waterfalls, etc., e. g., southwestern coasts of Maui and 
Hawaii. 
II. Cooler strands—windward, facing NE., N., or NW. 
8. All of the windward beaches. 
9. Slope more or less precipitous: high beaches, e. g., Hamakua 
coast, windward East Molokai, Napali and Nihoa. 
: ILLUMINATION 
The brilliant illumination of the Hawaiian strand is one of its 
most distinctive ecological features. The intense light of open 
beaches as contrasted with other regions, has been commented 
upon by ecologists in various parts of the world, but nowhere is 
this better exemplified than in the Hawaiian Islands. On the low 
islands the sky is cloudless, except during the infrequent rains. 
On the high islands the clouds heap over the mountainous interior, 
leaving the peripheral strand zone almost continuously exposed. 
The total insolation, in diurnal or in annual terms, is therefore © 
exceedingly high. The Hawaiian coast, with its excessive inso- 
lation, may be contrasted, for example, with the gray, foggy coast 
of Washington and Oregon. On the coral and tufa beaches the 
intensity of the direct illumination js greatly increased by reflec- 
tion. The glare on a coral beach, during the middle part of the 
day, as almost as intolerable to the eyes as that from a snow-field. 
There are few data as to the direct and indirect effects of ex- 
cessive insolation, save as an integral part of the xerophyte-pro- 
ducing complex. In general, light retards growth, and too great 
an intensity of light causes cessation of the growth of an organ. 
Pfeffer (’03, p. 87) states: 
