FRUIT DOTS 



159 



dies of the spermatophytes, but the stem is strengthened by the 

 masses of schlerenchyma tissue which can be readily seen. 



The leaves or fronds, as they are usually called, are very 

 similar in structure to the leaves of the Angiosperm. In fact, 

 the similarity is so striking that it is not necessary to describe 

 it at this time, but the student will do well to make a careful 

 study and comparison of the leaf with that of the Angiosperm. 



FIG. 97. A fern glade. 



(Chapter IV.) However, the leaves tend to unroll in a peculiar 

 manner (Fig. 98) which can be readily seen and- which is char- 

 acteristic of the ferns. 



Fruit Dots. On the under surfaces of many of the older 

 leaves will be found numerous fruit dots or sori (singular sorus). 

 (Fig. 99 and 100.) They vary greatly in size, character and 

 arrangement in the different species of ferns and in most cases 

 are covered with a delicate membrane known as the indusium. 



