32 



A MONTANE KAIN-FOREST. 



epiphytes, by far the most common are species of Elaphoglossum— 

 Elaphoglossum latifolium, Elaphoglossum inoequalifolium, and Elapho- 

 glossum petiolatum — together with the orchid Stelis ophioglossoides, 

 species of Dichcea, and the common bromeUad Caraguata sintenesii. 

 Throughout the forest Chusquea abietifolia forms thickets or cUmbs 

 over the lower trees, often making passage through the forest difficult; 

 the only other common lianes are Manettia lygistum, Cionosicys pomi- 

 formis, and Smilax celastroides. 



LEEWARD RAVINES. 



' The ravines of the leeward slopes of the Blue Mountains differ 

 strikingly from those of the windward side, exhibiting few of the most 

 pronounced characteristics of rain-forest. The general structure of 

 the two types is similar, both in the stature of their trees and in the 

 irregular canopy which gives place to abundant under-trees and shrubs. 

 Many of the same species of trees occur in the ravines of the two sides 

 of the range, and many of the epiphytes, but few of the terrestrial 

 herbaceous plants. The most striking difference between the two 

 ravine types is in the absence from those of the leeward side of garlands 

 of hanging moss and the beds of epiphytic mosses and hepatics, the 

 much scanter growth of epiphytes in general, together with the scarcity 

 of tree-ferns, the inconspicuousness of filmy ferns, and the predomi- 

 nance of herbaceous vegetation made up of a small number of fern 

 species of a less hygrophilous character and a number of flowering 

 plants. The leeward side of the range receives a lighter rainfall, has 

 much less fog, and a reciprocally increased number of hours of sunshine, 

 factors which combine to lower the atmospheric humidity and increase 

 the insolation to a degree that modifies fundamentally the life condi- 

 tions and makes the habitat an unfavorable one for very many of the 

 species so common in the Windward Ravines, at the same time that they 

 bring into the vegetation a number of trees, shrubs, epiphytes, and 

 other plants, the range of which extends down to 3,000 and 2,000 feet 

 (915 meters and 610 meters), but does not cross the main ridge onto the 

 Windward Slopes. By far the largest number of these middle-altitude 

 forms are absent from the Leeward Ravines and find their optimal 

 conditions in the still drier Leeward Slopes, on which the climate is 

 nearer that of the lower altitudes. 



The commonest trees of this habitat are Gilihertia arborea, Alcharnea 

 latifolia, Ilex montana var. occidentalis, BrunelUa comocladifolia, Psy- 

 chotaria brownei, and Psychotaria corymbosa. The commonest under- 

 trees are Bcehmeria caudata, Datura suaveolens, Phenax hirtus, Acnisttis 

 arborescens, Piper geniculatum, and Malvaviscus arboreus. The herba- 

 ceous vegetation is dominated by Pilea grandifolia and an assemblage 

 of species of Asplenium and Dryopteris — ^notably Asplenium pteropus 

 Asplenium lunulatum var. strictum, Asplenium obtusifoUum, Asplenium 



