675 
of the underground water level to the surface makes a common. habitat 
for plants which require this condition. Thus, irrespective of altitude, 
one finds plants which apparently belong to the low land extending up 
the stream as far as the habitat goes. Such trees as Sarcocephalus 
cordatus, Bischofia trifoliata, Mangifera altissima, and Bugenia luzo- 
nensis are found scattered from near the sea level up to an altitude of 
approximately 700 meters and they are seldom encountered in other 
situations. 
Ficus minahasse, other species of Ficus, Leucosyke capitellata, and 
Pipterus asper are encountered in similar situations from a point near 
the level of the sea up to 900 meters and Homonoya riparia grows in 
the bed of the stream itself up to the 500-meter line. (See Pl. XLII.) 
No doubt, many of these plants would flourish throughout the entire 
length of the stream, were the edaphic habitat which is necessary for 
their growth existent at higher altitudes. Aside from the edaphic mois- 
ture, the protected position of the cafion renders the atmospheric mois- 
ture more uniform and corresponding to this, trees and other plants 
requiring moisture conditions obtaining in higher altitudes are also 
present in low ones on the slopes of the canon farther down the moun- 
tain and, at these altitudes, such trees and plants are found in no other 
situations. The tree fern Alsophila contaminans, the very large An- 
giopteris crassipes, and other plants offer striking examples of this fact. 
(See Pl. XXIV.) Indeed, the vegetation of the river bed and of the 
cafions in any one climatic formation resembles that of similar habitats 
in the other formations more than it does that adjacent to it. As yet, 
the river habitat of the Lamao Reserve is a narrow one. As _ the 
mountain more nearly approaches base-level condition, flood plains will 
be established and thus the edaphic habitat having soil moisture near 
the surface will be enlarged. A comparison of the Lamao River vegeta- 
tion with that of the Bongabon River on the east coast of Mindoro, 
where the base-level condition has nearly been reached, shows that 
nearly all tree species, common and peculiar to the habitat near the 
Lamao River and on the lower slopes of the canyons, reach a much better 
development near the Bongabon River flood plain than they do near 
the Lamao River. Indeed, the vegetation of the Bongabon River flood 
plain is that of the Lamao River, spread out. Of course, this larger 
habitat offers space for more species, but practically all of those found 
on the narrow margin of the Lamao River are also present in greater 
numbers near the Bongabon and there give character to the vegetation. 
General conclusions.—Schimper °* has divided formations into cli- 
matic and edaphic, the one depending on the climate, the other on the 
conditions of soil; thus, within each general climate, there are peculiar 
conditions of soil such as those pertaining to the mangrove swamps and 
® Schimper: Loc. cit., 161 and 177. 
