PHILIPPINE DIPTEROCARPACEAE. 
235 
great extent. Dr. Wliitford 0 has shown that the dipterocarps in the 
Philippines frequently form almost solid stands over considerable areas. 
These stands are made up of several species. 
The trees are usually of large size, erect and comparatively free from 
prop-roots; although Pentacme , Anisoptera and some others do occasion- 
ally form fair-sized low, prop-roots. 
Time of flowering and fruiting. — It is because of our ignorance of 
this that our knowledge of the generic position, of some species is so 
vague. The gTeat size of ' many of the trees makes it a difficult matter 
to collect herbarium material from them. They stand out above the 
others in the forest and are much less likely to be covered with climbing 
vines. Much the most practicable method of collecting herbarium 
material, is by chopping the tree down. As the average collector is unwil- 
ling to take so much trouble, the material secured is often very frag- 
mentary, and material picked up under the tree does not furnish the 
safest indication of the condition of the plant. An indication of the 
time of flowering or fruiting is obtained by the finding of flowers or 
fruits on the ground under the tree. Very often the only fruiting 
material we have of a particular species has been so found. 
Indications seem to point to a very definite flowering season for some 
species and to a widely extended season for others. Dipterocarpus 
grandiflorus Blanco has been collected in flower in the months of J anuary, 
February, March, April, May, June, and December; and in fruit in 
January, February, May, June, August, and September. The variable 
climatic conditions in different parts of the Islands are probably respon- 
sible for this. Even in the same section, as in Bataan, there is a good 
deal of variation, perhaps due to soil, exposure and moisture conditions. 
This species and a number of others seem to flower regularly every year. 
There are some species, as Hopea plagata (Blanco) Yid., which are 
reputed to flower only once in several years. I think it likely that most 
species flower, at least partially, each year. 
When fruit is produced, it is found in great quantity ; but, there seems 
to be a very low percentage of germination. The seeds lie on the surface 
of the ground and germinate quickly, if at all. They seem to require a 
fairly constant and uniform amount of moisture for germination and the 
seedlings die quickly if exposed to the hot sun. It seems that the seeds 
occasionally germinate while still on the tree. Certain species, as Shorea 
eximia, contain fatty material in the seeds, which are greedily eaten 
by wild pigs and other animals. Such seeds as these disappear very 
quickly, within a few days after falling. 
Shortly after germination, the wings fall off and the thick, divided 
cotyledons are quickly raised on the long hypocotyl. 
“This Journal 4 (1910) Bot. 699-725. 
