254 
MERRILL. 
although open grass country is visible from the high ridges to the south 
of the mountain. The high forest, Dipterocarpus type is fairly well 
developed, extending up to an altitude of at least 500 meters, but . even 
this type is quite changed by its environment; terrestrial ferns, orchids 
and herbaceous plants being comparatively abundant and epiphytic plants 
numerous. The prevailing species of Dipterocarpus, ' Shorea , etc., disap- 
pear above an altitude of 500 meters, and Quercus llanosii, various species 
of Lauracece, Acer philippinum, Aralia, Casuarina sp., Englehardtia 
spicata, Artocarpus, Unond , Polyalthia , Weinmannia, Elceocarpus and 
many other aborescent genera appear, and epiphytic plants become more 
abundant. No less than twenty-two species of the genera Hymenophy- 
llum and Trichomanes are known from Halcon. 
At and above an altitude of 1,000 meters, the mossy forest type is 
encountered on the exposed ridges, at first confined entirely to the crest 
line, but as altitude is gained, extending down the lateral slopes for a 
greater or less distance. These crest-line forests are characterized by 
arborescent genera such as Agathis, Podocarpus, Dacrydium, Phyllocladus, 
Pinanga, Myrica, Drimys, Illicium , Neolitsea , Homalanthus, Ilex, Elce- 
ocarpus, Eurya, T ernstroemia, Adinandra , Mearnsia, Olethra , Vaccinium, 
Rhododendron, Symplocos, and others, numerous species of epiphytic 
orchids, ferns and other plants, and some terrestrial species, notably 
Burmannia longifolia, the ground, tree trunks and branches being densely 
covered with thick masses of mosses, lichens, etc., forming an ideal 
habitat for the abundant species of epiphytic and pseudo-epiphytic plants. 
The trees are more or less stunted and as altitude is gained this character 
becomes emphasized. Scandent or semiscandent species of Vaccinium, 
Diplycosia, Schefflera , Smilax , Calamus and Nepenthes clamber every- 
where through the dense ridge thickets and the fern Oleandra colubrina 
Copel., alone forms such dense masses that it is frequently difficult for 
the traveler to force his way through them. There is a constant change 
in the vegetation of these ridges as altitude is gained, some genera such 
as Drimys, Podocarpus, Nepenthes, Phyllocladus, Agathis, Symplocos, 
etc., persisting unaltered from an altitude -of 1,000 meters to the summit 
of the highest peak, but terrestrial and epiphytic orchids, ferns and 
other plants entirely change, those at the higher altitudes being quite 
different from those at the lower ones. Mosses and lichens become more 
abundant and form much thicker and denser masses on the ground 
and trees, whereas Sphagnum appears in the ground cover. There is 
less diversity in constituent species on the highest ridges above 2,400 
meters than at lower altitudes, but the trees and shrubs on them are 
greatly stunted, being reduced to montane brush which rarely exceeds 
a height of 3 meters. Epiphytic and terrestrial plants .become reduced to 
comparatively few species and individuals, while mosses and scale mosses 
correspondingly increase in abundance and diversity of forms. 
