188 The Philippine Journal of Science leir 
grasses have a running habit. These grasses and sedges are so 
small and scattered that even at a short distance they are not 
noticeable and the ground that they occupy appears to be quite 
bare. An exceptional development of them is shown in Plate 
VIII, fig. 2. 
In the extreme northern part of the island and at the tip of the 
peninsula, which projects from the southwestern corner, there 
are some very steep slopes. In these places another tall grass, 
Themeda gigantea, predominates; and erosion is apparently 
not very rapid at the present time. Themeda is confined largely 
to the various steep slopes, which are at a considerable distance 
from the crater, and in such places it makes a better growth than 
Saccharum. At the present time Themeda occurs mostly in dense 
stands. It is most prominent on Mount Binintiang Malaqui and 
the neighboring horseshoe ridge. Mount Balantoc. In both of 
these places the stands are frequently so dense that it is extreme- 
ly difficult to walk through them. 
In a limited region in the northeastern corner of the island, 
between Mount Bignay and Mount Ragatan, and at the north- 
western corner near the former village of Pirapiraso, Imperata 
cylindrica, a much smaller grass than either Saccharum or 
Themeda, covers the ridges and some of the slopes. The valleys 
in this region are occupied by Saccharum. Imperata cylindrica 
is a very common grass on the mainland around Lake Bombon, 
and so it seems surprising that its distribution on Volcano Island 
should be so limited. This is particularly so, because Impei'ata 
usually occurs on dry ground. On the parts of Volcano Island 
where Imperata and Saccharum occur together, they occupy the 
same relative positions that they usually do on the mainland; 
that is, Imperata in the drier and Saccharum in the moister 
situations. However, in other parts of the island Saccharum 
occurs in situations that appear to be dryer than those occupied 
here by Imperata. 
Another case of a peculiar distribution of a grass is afforded 
by Miscanthus sinensis. This tall grass usually occurs at high 
altitudes in places where the soil is moist and the evaporation 
low. In such situations it frequently forms extensive dense 
stands, which result from fires in the same manner as do those 
of Saccharum spontaneum at low altitudes. On Volcano Island 
this grass is mainly confined to small patches, which occur on 
the sides of the ravines and are frequently only a few meters 
above sea level. The total area occupied by this grass is very 
small. 
