<r: 
648 
meters, although they seldom are taller than 8. Rubiacew which do not 
reach above 4 meters occur as scattered specimens of the genera Anoxia 
and Urophyllum, which are better represented on the exposed ridges at 
greater altitudes. 
Besides the larger trees of the Theaceew, namely, Gordonia fragrans 
and Ternstroemia toquian, the smaller one, Thea montana is very com- 
mon as undergrowth. Memecylon edule of the Melastomatacee, which 
is also conspicuously encountered in all three formations below that of 
the Shorea-Plectronia, is very common in this portion of the Reserve; 
indeed, here it reaches its best development in size and numbers. 
Relation of the composition of the forest to topography.—The varia- 
tion in the composition of the forest, just as is the case in the formations 
previously discussed (excepting in the parang types, which are due to 
artificial conditions),: depends in the main on the physiographic situa- 
tion. The topography in this situation is rougher than it is in the forma- 
tions found at lower altitudes. This prevents the vegetation from 
reaching the luxuriant condition which it would have in a similar climate 
but with a more stable topography; that is, at a point nearer base level 
with its accompanying conditions. Again, as compared with lower 
situations, the higher altitude of this formation renders any exposed 
position more subject to the influence of winds, and thus a tendency 
toward a dwarfed condition in the vegetation is brought about. It has 
already been shown that the vegetation of a ridge peak (see p. 641) in 
the Dipterocarpus-Shorea formation is partially dwarfed, and for Mari- 
veles Mountain this tendency reaches its climax in one to be discussed 
below and designated as the Hugenia-Vaccinium, but in comparison 
with the latter it is much less pronounced in the formation under 
discussion. At an altitude of 760 meters there appears an exposed 
ridge peak which has a thin soil and a strikingly xerophytic vegeta- 
tion, which contrasts with the more protected one found in a slightly 
lower saddle near by. Here members of the Dipterocarpacew are entirely 
absent, although present in other situations at the same altitude within 
the formation. Ternstroemia toquian, Thea montana, Quercus sp., 
ERugenia robertii, and other species which are here encountered show a 
leaf surface much reduced from that which they present when they 
grow at an identical elevation in more favorable positions. The ruta- 
ceous Acronychia laurifolia with hard, and during the dry season, 
partially deciduous leaves, the rubiaceous Vricalysia sp., and the melas- 
tomaceous Memecylon affine, both shrubby and with hard leaves, are 
among the common forms met with in similar physiographic situations 
at a greater altitude on the mountain. Mingled with the above may 
be found Scolopia luzonensis, Atalantia disticha, and Buchanania florida, 
all found in xerophytic positions in the Anisoptera-Strombosia forma- 
tion. Buchanania is especially marked by its very much reduced leaves. 
(Pl. XLII, A). Sterculia montana is the only tree noted which for 
