x, c, 3 Merrill: Botanical Exploration of the Philippines 165 
density of the very complex vegetation, the abundance of vines, 
and the frequent occurrence of epiphytes in great quantities, 
especially above 600 meters altitude, all add to the difficulty of 
making an exhaustive collection or a collection that shall contain 
representatives of all the species found in a given area. Again 
one must take into consideration that a considerable number of 
species are irregular as to periods of anthesis, and may flower 
but once in several years, as many of the bamboos, or, like the 
buri palm (Corypha ) , but once in the life of the plant, which 
may be twenty-five years or more. While the period of anthesis 
of some species may extend over several days or weeks, other 
plants produce very ephemeral flowers, and such species may be 
entirely overlooked in a botanical survey of a given region unless 
the collector is so fortunate as to locate the species during its 
short period of anthesis. 
In general, any collector should endeavor to secure a represen- 
tative of all the species found in flower or fruit in the region in 
which he is working. However, it is well to make a distinction 
in regard to the regions to be first explored. In view of the 
data given above it is manifest that little of botanical interest 
will be found along the seashore, or anywhere at low altitudes 
in the Archipelago where the vegetation has been much disturbed 
by man ; that is, the cultivated areas, waste places in and about 
towns, the open grassland, and the so-called parang, those areas 
covered with thickets and second-growth trees. Most of the 
species found in such regions are common, widely distributed, 
and thoroughly well known. The collector should give his most 
serious attention to the virgin forest and to the various types 
of vegetation found at and above an altitude of about 600 meters, 
for it is only in the virgin forest, or at medium and higher 
altitudes, that he can expect to find any high percentage of 
novelties, or species of special botanical interest. 
Immense areas occur in the Philippines from which not a single 
botanical specimen has been secured. For those regions at low 
altitudes that are for the most part deforested, botanical explora- 
tion would be of little value, for the reasons already given. Thus, 
large parts of the Provinces of Cagayan, Isabela, Pangasinan, 
Tarlac, Pampanga, Bulacan, Nueva Ecija, Batangas, Tayabas, 
Cavite, Camarines, Albay, and Sorsogon in Luzon, and like areas 
on the Islands of Mindoro, Marinduque, Masbate, Catanduanes, 
Panay, Negros, Cebu, Bohol, and parts of Mindanao and Palawan 
will not repay botanical exploration; yet in every province and 
island mentioned where virgin forest exists, whether at low, 
