VEGETATION OF THE RAIN-FOREST. 25 



prominent part of the herbaceous vegetation, with species of Pilea 

 and Peperomia in the minority and terrestrial orchids not abundant. 

 Species of Rynchospora and the endemic sedge Uncinia hamata are not 

 infrequent in more open situations, but the sedge and grass types are 

 unconmion on the whole, as are also monpcotyledonous plants in 

 general. The absence of palms and of the musaceous type of large- ^ 

 leaved phanerogams in general, taken together with the presence of 

 tree-ferns and filmy ferns and the general predominance of bryophytes 

 and pteridophytes, marks the salient features of this type of rain-forest. ■ 



In the abundance of its epiphytic vegetation the rain-forest is trop- 

 ical in character. Tank epiphytes of the bromeliaceous type are com- 

 mon, although represented by but few species; large woody forms are 

 not frequent. Orchids, with either water-storing leaves or storing 

 roots, are common, but are not so frequent as the ferns, which range 

 from large hygrophilous forms to small xerophilous ones, including 

 notably a number of species of Hymenophyllacese. A large part of 

 the bulk of the epiphytic vegetation is made up of mosses and hepatics, 

 which serve as a water-retaining substratum for the larger forms. 



The representation of lianes is poor, particularly outside the ravines, 

 where Marcgravia and several asclepiadaceous forms occur together 

 with the low-growing climbing ferns, species of Polypodium and Blech- 

 num. The scrambler Chusquea is abundant in the open forest of slopes 

 and ridges. 



The continuity of the forest formation is broken by occasional land- 

 slips and by the thickets of scrambling ferns along the ridges and on 

 the highest peaks. On the northwestern face of Sir John Peak, near 

 its summit, and on the same face of Mossman's Peak are also patches 

 of a coarse bunch-grass {Danthonia shrevei), which has not been col- 

 lected elsewhere in the island. It grows in large hummocks (see plate 

 19), and is accompanied by scattering plants oi Gleichenia, with dwarf 

 individuals of Clethra alexandri, Ilex obcordata, and Weinmannia 

 pinnata about the edges. The areas are not old landslips, the char- 

 acter of their soil is not peculiar, neither are they exposed to conditions 

 any more adverse to tree growth than those operative on the peaks 

 themselves. It is impossible to gain any notion whether the areas are 

 encroaching on the forest. The habit of the grass is such as to cover i 

 and completely shade the ground, and seedlings of other plants are 

 rare between the hummocks. The rapidity of the erosion now going 

 on makes it highly probable that in recent geological time the Blue 

 Mountains extended considerably above their present altitude. At a 

 time when these two peaks were loftier they would, in all probability, 

 have borne alpine grassland above the tree limit, such as Volkens^ 

 encountered on Kilimandjaro at 7,800 feet, less than 400 feet higher 

 than the summit of Blue Mountain Peak, and at 15° lower latitude. 



^Volkens, G., Der Kilimandscharo. Berlin, 1897. 



