ix, c, 5 Gates: Pioneer Vegetation of Taal Volcano 407 
Phragmites, radiating in all directions but particularly along 
the shore, are tending toward its rapid establishment, but the 
presence of seedlings of trees, undoubtedly established, bespeak 
the probable early elimination of the Phragmites association in 
these situations. 
On the deltal flats, the individual plants of Phragmites are 
widely spaced, yet secondary species are so nearly absent that 
successional tendencies are hardly indicated. It is possible for 
the ground to become dominated by Phragmites or by Acacia 
farnesiana, which is very abundant in the immediate vicinity, 
or in the case of a lowering of the water table level by Sac- 
charum spontaneum, the most abundant plant on the island. 
Thus the three years since the eruption have resulted in only 
a poor representation of this series of associations in spite of 
the fact that there is a large amount of apparently suitable 
ground. The excellent drainage developed in the mud and ashes 
probably has considerable to do with this. 
THE DRYGROUND GENETIC SERIES 
In this series belong the associations which vegetate the 
drained ground. On this island they are far in the ascendency. 
Four formations can easily be recognized, namely, the strand, 
the grassland, the shrub, and the tree formations, all normal to 
the Philippine area in the Indo-Malayan plant province. 
THE STRAND FORMATION 
THE IPOMOEA PES-CAPRAE ASSOCIATION 
This well-known association has been described previously 
for a sea coast locality in the Philippines by Whitford . 6 Al- 
though the strand on Taal is a fresh water habitat, the structure 
of the vegetation is essentially similar to that of the salt water 
strand. The two dominant species of this association on Taal 
Island are Ipomoea pes-caprae and Canavalia lineata. These 
are so similar in growth form and color that it is impossible to 
distinguish between them at a distance unless they are in flower. 
The plants trail over the ground for long distances, sometimes 
more than 45 meters, rooting freely at the nodes. They tend to 
extend into the water and maintain a sharp tension line with the 
limit of severe mechanical injury by storm waves. In this 
respect Ipomoea is hardier than Canavalia. Landward the 
b Whitford, H. N., The Vegetation of the Lamao Forest Reserve, Philip. 
Journ. Sci. 1 (1906) 666. 
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