676 
Genetic relations of tidal vegetation.—lt has been seen that the tidal 
estuaries of young rivers in the first stages show elements of the Nipa 
vegetation and that this is followed by the mangrove proper. As the 
delta formations grow, the mangrove captures the newly made portions 
and it thus steadily advances seaward. In the meantime, the landward 
portions of the swamps are being filled by the normal erosive forces and 
thus the habitat changes and with it, as a consequence, the plant forma- 
tions. Thus the zone of vegetation behind, replaces Nipa and the latter. 
in turn advances on the mangrove. For the Reserve, this is the parang 
of the region immediately behind these swamps. Had the original 
vegetation in this situation not been removed, then it would take posses- 
sion. Thus extensive areas, especially the deltas of large rivers which 
formerly were occupied by mangrove and Nipa swamps, are now covered 
with the mesophytic forests. 
Sea-cliff formation.—The vegetation of the sea cliffs has no species 
peculiar to this situation ; rather it partakes of the characteristics of the 
sandy beaches and of the regions behind them. The windy nature of the 
habitat evokes a strictly xerophytic type. Trees such as Vitex littoralis 
(molave) (See Pl. XLI), which often occupy a place on the very edge 
of the cliff, show a much more stunted growth than those in less exposed 
places. Hrythrina indica, Terminalia catappa, and, Pandanus tectorius of 
the beach plants often find lodgment on the cliff. The inland formation 
furnishes Parkia roxburghii, species of bamboo, Celtis sp., Scolopia 
luzonensis, Linociera cumingiana, Mimusops elengi, Cyclostemon, cu- 
mingit, Cordia blancoi, Memecylon edule, Glochidon littorale, Hrioglossum 
rubiginosum, and others. 
GENERAL CONSIDERATIONS. 
Relations to climate-—It has been shown that as one ascends the 
mountain from the seashore to the summit, distinct climatic belts are 
encountered and corresponding to these belts are plant formations. ‘The 
elements of the climate which leave their imprint on the type of vegeta- 
tion are distinctly those of moisture. From the base up to and including 
the top, the rainfall and the relative humidity increase and the heat 
slightly diminishes as one proceeds from below upward. Save on the 
exposed ridge where the wind causes excessive transpiration, the climatic 
conditions are for this reason rendered more favorable to vegetation and 
therefore, one finds a forest more nearly evergreen situated well up on 
the mountain than one does at its foot and correspondingly, the deciduous 
and bamboo elements become less pronounced. It may seem presump- 
tuous at this time to make comparisons with the vegetation of other por- 
tions of the Islands, vet a hasty trip to parts of the east coast of Luzon 
previous to and valuation surveys made on the east coast of Mindoro 
since the collection of data for this paper, clearly show that the climatic 
formations found well up the slopes of Mount Mariveles are in both the 
