f 
THE FLORA OF MANILA. 151 
Assuming, then, that the original vegetation of the Philippines 
was practically unbroken forest, it becomes manifest that a 
very high percentage of the species now dominant in the settled 
areas, that is, in waste places in and about towns, fallow fields, 
cultivated areas and thickets, and in the open grass country, 
must have been introduced into the Archipelago after the advent 
of man and after sufficient time had elapsed for man to have 
provided the habitats to which these species are adapted. The 
great bulk of these plants are those requiring abundant light, 
' adapted to growth in the open, and which cannot persist under 
forest conditions. They are for a large part species of very 
wide distribution that certainly have not originated in the Archi- 
pelago, but which must have developed their characteristics 
as to habitat in non-forested, or at least very thinly forested 
countries. 
On the assumption that the great majority of the species now 
found at low altitudes in the settled areas of the Philippines 
have reached the Archipelago by one means or another since 
the advent of man, it is manifest that should any large area 
become depopulated for a long term of years, and the vegetation 
thus become protected against fires and other disturbing factors 
due to the presence of man. the original vegetation of the Archi- 
pelago would again occupy the entire area. The absolute or 
nearly absolute extermination of the introduced forms which 
depend for their existence on an open habitat, and which cannot 
thrive in forests, would follow. This would mean that the great 
majority of the species now found in the settled areas would 
become either extinct, or of rare and very local occurrence 
in the limited areas where conditions for their growth and re- 
production might persist. In addition to the herbs, undershrubs, 
and other plants of the country, now so common and widely 
distributed, which would in all probability be exterminated with 
j the reversion of the country to primeval conditions, it is exceed- 
; ingly probable that very many of the introduced trees, including 
the naturalized ones, would eventually become extinct, from 
their inability to withstand forest conditions, that is, their 
inability to compete with the native trees and vines in the 
struggle for light. 
In Table I, following, is given a summary of the species con- 
^ t sidered in the "Flora of Manila," a total of 1,007 distributed 
into 595 genera and 136 families. Of these 1,007 species it is 
estimated that about 550 are indigenous, that is, true natives 
of the Archipelago or those that have reached the Islands through 
I 
