THE FERNS OF NICARAGUA. 1T g 



volcanic rock become so dry that thev mav be ground to 

 powder between the fingers, and yet they retain life, while in 

 the eastern part, with its deep jungles in which perpetual 

 shade and moisture prevail, the more delicate as well as the 

 more gorgeous forms have full opportunity for the develop- 

 ment of their many peculiarities. 



The fierce struggle for existence which is constantly going 

 on between the members of the vegetable world in this land 

 of abundant moisture and perpetual summer has left its impress 

 upon the flora in general. In the dense jungles the necessity 

 of reaching upward to the realm of sunlight has resulted in 

 the development of a distinct aerial flora, of which Ferns form 

 by no means an inconspicuous portion. 



This upward tendency on the part of the Ferns manifests 

 itself in a variety of ways. Some species, as Acrostichum sor- 

 bifoliitm and A. ostnundaceum send their rootstocks upward 

 along trunks of trees or shrubs, often to a height of several 

 feet, the rootstocks in some species bearing scattered fronds 

 at intervals, in others being crowned at the tip with clusters 

 of fronds. 



Sometimes the part which connects with the soil dies away 

 and an epiphyte results. That this has been the origin of 

 epiphytes seems evident. In the course of their development 

 as they advanced with the growth of the supporting plant the 

 topmost branches of the tallest trees were ultimatelv reached, 

 and spores scattered in this upper region bv the wind, gave 

 rise to an extensive aerial flora. 



Another line of development however resulted from the 

 struggle for light, if we are to judge from present indications. 



Some such climbing Ferns, instead of severing their connec- 

 tion with the soil, and resting whollv upon the stem of the sup- 

 porting plant, sometimes find that the support is destroyed 

 and as a result, if the rootstock is not too long, and if it is 

 sufficiently strong, which is often the case in the tufted forms, 

 the fern remains erect sustained whollv by its rootstock, thus 

 producing the effect and offering the first suggestion of a tree- 

 fern. 



