THE FERNS OF NICARAGUA. I2 i 



Since in addition to about 600 species of flowering plants 

 about four-fifths of the reported number of Ferns were col- 

 lected in so short a time, several of the species being new to 

 the reported flora, and as the regions both north and south 

 of the San Juan Valley have shown much richer floras upon a 

 more careful investigation, it is safe to assert that scarcely 

 more than a beginning has been made in the botanical studv of 

 this interesting region. In all cases care of course must be exer- 

 cised in making use of locality lists as a basis for general con- 

 clusions, since the local distribution of ferns is quite as charac- 

 teristic as that of tropical flowering plants, and none of the 

 localities from which lists have heretofore been published have 

 been sufficiently thoroughly worked to furnish full data. The 

 need of such thorough work is made apparent when we con- 

 sider the scattered local distribution of plants in general in 

 tropical forests. Speaking of tropical forest trees, Wallace 

 says : x 



" If the traveler notices a particular species and wishes to 

 find more like it. he mav often turn his eyes in vain in every 

 direction. Trees of varied form, dimensions and colors are 

 around him, but he rarely sees any one of them repeated." 



This scattering of individuals is probably a result of the 

 sharp struggle which is going on in the tropical vegetable 

 world under the most favorable conditions of heat and moist- 

 ure, the strongest individuals of each kind, only being able 

 to hold their own. Whatever mav be the cause, the fact is 

 striking, and the collector will often find it almost impossible 

 to secure a large series of a species in one locality, while the 

 variety of forms is quite bewildering and the slightest change 

 in locality brings to him repeated surprises. 



Not more than fifteen species in the following list are ex- 

 tensively gregarious, and in the more tvpical tropical forests 

 of Castillo and Greytown no species was found which would 

 compare in gregarious habit with the majoritv of the ferns of 

 our northern forests. 



1 Natural Selection and Tropical A 7 'at u re, p. 267. See also pp. 23S-269 for a 

 general account of tropical vegetation. 



