512 The Philippine Journal of Science 1914 
8 per cent of the individual plants are Acacia, 90 per cent are 
Acrostichum, and the remaining 2 per cent are distributed 
among Premna, Phyllanthus, and a few vines. Farther from 
the hot springs the Acacia consocies mixes with the Premna 
consocies and may even be more or less replaced by it. 
In the Tarlac area a fringe of Acrostichum generally separates 
Acacia from the main body of the marsh. Into this, Acacia 
readily invades and obtains dominance. The appearance is not 
entirely typical for other shrubs have also invaded with the 
result that the area is mostly a jumble of the Acacia and Premna 
consocies of the parang association with the Acrostichum and 
Phragmites associations. Irregular setbacks have interrupted 
and often reversed the normal trend of succession. In spite of 
this fact progress in shrub invasion is evident. 
The Premna consocies.—The Premna consocies represents the 
highest vegetation at present in the Los Bafios area. It is a 
consocies of the parang association dominated by Premna odo- 
rata Blanco, associated with the usual promiscuous vines. 
Nowhere is this consocies well developed as yet, as it is in a 
transition stage in which the Premna is gradually assuming 
dominance because of its more advantageous growth form. 
In the Tarlac area Premna is following Acacia, but very slowly 
on account of the frequent setbacks. 
The Pithecolobium consocies.—Along the railroad in both 
areas a few trees of Pithecolobium dulce Benth. serve to indi- 
cate the presence of the Pithecolobium consocies of the parang 
association. 
The Gliricidia consocies—Where low knolls occur in the 
boundary of the hot-springs area, especially near the railroad, 
the shrubby vegetation is frequently composed of thickets of 
Gliricidia sepium Steud. The consocies is typically developed, 
a dense growth of Gliricidia, with relatively few secondary 
species. Back of it is usually cultivated land. 
The general parang association—As more and more of the 
typical parang species invade and spread over an area, the more 
mixed the vegetation becomes, until it is no longer possible to 
distinguish consocies. The parang is then in the prime of its 
development, and may be termed the general parang. In the 
Swamp areas there are very few spots which have arrived at this 
stage, although, back from the swamp areas on the adjacent dry 
land, the tendencies in that direction are very obvious. A large 
number of species go to make up this jungle, the most abundant 
of which are here listed: 
