390 Philippine Journal of Science 1920 
codominant with the dipterocarps, but by far a greater majority are sub- 
dominant species, some of which have ill-formed boles, much smaller in 
diameter and length. Underneath the dominant and subdominant species 
are a large number of undergrowth tree species which do not attain more 
than 10 centimeters in diameter when mature, and a height of 10 meters 
or less. From a botanical point of view, these add greatly to the com- 
plexity of the forests, but for commercial considerations they should be 
called undergrowth trees. Within the forests there are comparatively 
few shrubs, or bushes, and herbs. 
All the types of dipterocarp forests contain climbing palms (fattans), 
but the number and size of other large vines (lianas) seem to diminish 
with the prominence of the dipterocarps. Artificial and natural openings 
in the forests are often covered with a jungle of climbing bamboos and 
other large lianas, and the edges of the forests especially along streams, 
present breast-works of twisted vines which are very difficult to penetrate; 
but as soon as the interior is reached it is easy to pass through the 
forest with only the occasional use of a bolo (machete).* 
Dipterocarp forests are best developed on well-watered plains 
or on the lower slopes of large mountains. Here the soil is 
usually a deep loamy clay of volcanic origin; passing to drier 
soils of calcareous origin the dipterocarp species give way and 
the forest becomes more open, usually dominated by such species 
as molave, Vitex parviflora Jussieu. As higher elevations are 
reached the trees become smaller and the dipterocarps less nu- 
merous. At 800 meters or less this type gives way to one in 
which miscellaneous trees—Quercus and other genera—are more 
prominent.*® 
Brown * has written a careful description of the forests of 
Mount Maquiling, Laguna Province, Luzon, in which is included 
a vast amount of detailed and exact information. The volume 
and the composition of the forest at different altitudes are given 
with great care, and the book is a unique study of tropical 
vegetation. 
MOLAVE TYPE OF FOREST 
Molave, Vitex parviflora Jussieu, is fairly well distributed 
throughout the forest that is designated the molave type. It 
is found typically on low limestone hills, which are usually com- 
posed of crystalline coral limestone with a honeycomb structure. 
These rocks are generally covered by shallow or scanty soil. 
The habitat is very dry. A large part of the molave type has 
“ Whitford, H. N.j Bull. P. I. Bur. Forestry 10* (1911) 18. 
“See Brown, W. H., and Matthews, D. M., Philip. Journ. Sci. § A 9 
(1914) 416. 
"Vegetation of Philippine Mountains. Bureau of Science, Manila 
(1919) 434 pp., 41 pls. 
