98 THE AMERICAN BOTANIST. 



In the method of fruiting, too, this group is pecuHar. In or- 

 dinary ferns the spore cases are to be found on the under side 

 of the leaves in tiny groups of various shapes, but Acrostichuni 

 seems dominated by the principle that what is worth doing at 

 all is worth doing well and when it sets out to fruit, it spreads 

 the entire under surface of the spore-bearing fronds with 

 spore-cases, while in a few species a finishing touch is put on 

 the job by the addition of a coating of spores on the upper 

 side of the frond as well, a trick that other families of ferns 

 do not seem to know. Spore-bearing is serious business with 

 Acrostichiim and in some of the species with finely divided 

 fronds, the fronds which bear the spores are made broad, and 

 entire so that there shall be plenty of room for the spore-cases. 

 A similar method of bearing spores is found in the stag- 

 horn ferns {Platyccrium) of the green houses and faint traces 

 of it are seen in such genera as Gynmo gramma and Lomaria 

 which is regarded as an indication that all these genera are 

 rather closely related. 



The habitat and habit of the plants are as varied as their 

 other characteristics. Some live on the earth in exposed 

 places, others may be found on the branches of trees and 

 others, unable to find a perch on the branches, send their stems 

 straight up the trunks to a considerable height or creep among 

 the mosses on old logs. Those that live on trees are among 

 the most interesting since their fronds are decorated with soft 

 browm scales that are often so abundant as to conceal the green 

 tissues below. In others the scales are restricted to a delicate 

 fringe on the margin of the fronds. Those that live in the soil 

 usually do not have these scales, from which it is apparent 

 that the scales are useful to the epiphytic species in aiding the 

 fronds to retain their moisture. 



The smaller Acrosticliiims are not more than two or three 

 inches high, and the species with simple leaves rarely have 

 fronds more than two feet long, but some of the other mem- 



