THE FLORA OF MOUNT PULOG. 
305 
perhaps not really specifically distinct from Pinus khasya Royle, of the 
'mountains of Khasia, Chittagong, and Burma. In the Philippines. 
Pinus insularis Endl. is widely distributed in the present Mountain 
Province, extending northward from southern Benguet through Lepanto, 
Bontoc, and Abra subprovince as well as parts of Iloeos Norte and 
somewhat eastward into Nueva Vizcaya, a homogeneous area; an isolated 
and restricted area is found in the mountains of Zambales Province, 
Luzon, while the allied species, Pinus merkusii DeVr., is found also 
in Zambales Province and in western Mindoro. So far as our general 
collections from Zambales and the pine region of Mindoro show, at 
least some of the other species, associated with the pine in the Benguet- 
Lepanto region are also found in these two localities. As a rule, however, 
the species so characteristic of the Benguet-Lepanto region are not found 
south of the mountains limiting the southern boundary of Benguet. 
Occasional ones, such as Pinus insularis Endl., Deutzia pulchra Vid., 
Microlaena stipoides R. Br., Sageretia theezans Brongn., Senecio luzo- 
niensis Merr., and Lobelia nicotianaefolia Heyne, are found also on the 
higher mountains of the Zambales range, while others, such as Taxus 
baccata subsp. wallichiana Pilg., Oirsium luzoniense Merr., Ainsliaea re- 
flexa Merr., etc., extend still farther southward to Mount Banajao ; still 
others are found on Mount Halcon, Mindoro, including Drosera peltata 
Sm., Vaccinium barandanum Vid., Ainsliaea reflexa Merr., Isachne pan- 
gerangensis Z. & M., and Arundinaria niitakayamensis Havata. This 
southern range is not surprising when it is considered that the altitudes 
of all of the mountains discussed approximate that of the average peaks 
in the Benguet-Lepanto region. Moreover the Zambales range, although 
separated from the central cordillera by the Pangasinan-Pampanga 
plain, is distinctly visible from the higher peaks of Benguet, even from 
such distant ones as Pulog, while the central cordillera forms a nearly 
complete connecting chain with Mount Banajao. The absence of the 
majority of the characteristic species of the Benguet-Lepanto region 
from peaks of approximately the same altitude situated farther to the 
south, is probably largely due to unfavorable climatic conditions, such 
as relatively higher temperatures, differences in exposure, rainfall, humid- 
ity, etc., and also to the fact that on these southern mountains, at 
least on their more tropical lower and medium slopes, the struggle for 
existence among the various species is much greater than in the elevated 
comparatively temperate Benguet-Lepanto region. 
The Benguet-Lepanto region, as intimated above, is characterized by a 
great number of species that must be considered as of continental or 
Asiatic origin, rather than as Malayan types. Some data regarding the 
northern element in the Philippine flora have previously been published , 5 
5 This Journal 1 (1906) Suppl, 174-17.7. 
