VEGETATION OF THE RAIN-FOREST. 39 



higher and more constant humidity at the floor in the mountain forests. 

 The epiphytes of the lowest level are pronounced hygrophytes, confined 

 to that level by its favoring conditions of humidity and frequent 

 wetness. The mid-level forms are somewhat drought-resistant or else 

 confined to the proximity of water-storing mats of bryophytes, or 

 they may have a water-storing tissue. The epiphytes of the topmost 

 level are pronouncedly xeroplulous, with either water-storing or water- 

 catching structures, or else they are small and coriaceous. 



The Windward Ravines exceed by far all of the other mountain 

 habitats in the wealth of their epiphytes, because in them can be found 

 not only their own pecuUar forms, but in the tops of the tallest trees 

 are to be found the forms characteristic of the Ridge Forests, while at 

 mid-height in the Ravines are to be found those characteristic of the 

 Slopes. 



The commonest terrestrial ferns, orchids, and species of Pilea are 

 not very commonly found as epiphytes, even at the lowest level in the 

 forest, but the succulent Peperomias — Peperomia hasselcejolia and Pepe- 

 romia filiformis — with the non-succulent Peperomia hispidula, are low 

 epiphytes, growing with Trichomanes capillaceum, Trichomanes hookeri, 

 Trichomanes pyxidiferum, and Hymenophyllum fucoides. Such filmy 

 ferns as Hymenophyllum asplenioides, Hymenophyllum tunhrigense, 

 Hymenophyllum crispum, and Hymenophyllum polyanthos grow fre- 

 quently on rather bare trunks, as do also Polypodium suspensum and 

 Polypodium cuUratum, forms distinguishable by their pendant fronds. 

 In the case of the majority of forms, however, which occur more than 

 a few feet above the ground, the existence of a moss substratum is 

 essential to their occurrence. The more resistant filmy-ferns, Hymeno- 

 phyllum polyanthos, Hymenophyllum crispum, and Hymenophyllum fuc- 

 oides, are very common at middle elevations in the forest, growing in 

 beds of liverworts, beneath which such pendant forms as Hymeno- 

 phyllum sericeum, Hymenophyllum axillare, Elaphoglossum squamosum, 

 and Elaphoglossum villosum are common in occurrence. 



The largest of the epiphytes is Sciadophyllum brownei, an araliaceous 

 plant sometimes growing independently, sometimes a half-climber, but 

 more frequently epiphytic at mid-level in company with the gesner- 

 aceous Columnea hirsuta and the melastomaceous Blakea trinervis — 

 also often rooted in the soil. Seedhngs of Clusia havetioides are also 

 frequent as epiphytes, seedhngs of other trees being rare off the ground. 

 Peperomia obtusifolia var. is conspicuously frequent, as are also some 

 of the numerous species of Elaphoglossum (Elaphoglossum latifolium, 

 Elaphoglossum incequalifolium, and Elaphoglossum pallidum) and the 

 striking Lycopodium taxifolium. The larger epiphytic orchids are very 

 numerous, although there are but few species of them. Stelis ophio- 

 glossddes and Dichcea graminea are forms with water-storing leaves 

 and thin roots, while Dichcea glauca has thin leaves and stout roots with 



