514 The Philippine Journal of Science 1914 
THE BAMBUSA-PARKIA ASSOCIATION 
Although not an integral part of the swamp vegetation, the 
Bambusa-Parkia association was found on dry land above the 
high-water level bordering parts of the western and southern 
limits of the Tarlac area. It is a very common association 
along Lake Bay, where it is one of the most important back- 
strand elements. It is present near, but not at, the mouth of the 
Casilihan River. Along streams that run from hot springs to 
Lake Bay, the Bambusa-Parkia association is not present, whereas 
in the lower courses of streams coming directly from the moun- 
tain the banks are always lined with bamboo, Bambusa blumeana 
Schultes. 
CONCLUSIONS 
1. Just west of Los Baiios, Laguna, P. I., at the foot of Mount 
Maquiling, is a low swampy area fed by mountain streams and 
hot-water springs. The area has been under constant observa- 
tion and study since September, 1912. 
2. In the hot water, as it issues from the ground, there is no 
vegetation. The highest temperature recorded was 91.2° C. 
Bacteria and blue-green algae inhabiting the bottom of the pools 
appear when the temperature of the water is lowered to 56°. 
Surface algae develop in water whose temperature does not ex- 
ceed 52°. Among the higher plants, only Bacopa monniera 
Wettst. and Fimbristylis spathacea Roth will withstand a water 
temperature as high as 48°, 
3. Higher and lower hot-water levels at different times of year 
are accompanied by advances and retreats of the plant associa- 
tions in the immediate vicinity of the hot springs. 
4, Eighteen normal swamp associations are present in the area; 
three additional associations invade on the margins where con- 
ditions permit. 
5. Of the eighteen swamp associations, but one is characterized 
by woody species. All of the swamp associations are character- 
ized by a large number of individuals of a very few species. 
6. While the greater part of the swamp is vegetated with marsh 
vegetation (grass and more or less grasslike, wet-ground pre- 
ferring plants) the successions tend toward the development of 
a swamp forest except in the immediate vicinity of the hot 
springs. 
7. The readiness with which normal strand plants occupy 
space in the swamp is noteworthy. The presence of vines and 
lianas under the most diverse conditions is a conspicuous feature 
of the area. 
