—29— 



z 



3 



attacked the 

 plant. (Fig. i.) 

 Under a magni- 

 fier these dots 

 and lines are 

 resolved into 

 heaps of tiny- 

 globes (Fig. 2), 

 which are usu- 

 ally attached to 

 the leaves by a 

 short stalk (Fig. 

 3.) In these 

 globes the 

 spores are de- 



veloped, and from them comes the first generation of the fern. 

 The heaps of globes are called sort '( singular, sorus), and the 

 globes themselves are called sporangia. Sometimes the young sori 

 are covered with a thin membrane called the indusium and this 

 should be remembered, as it plays an important part in the iden- 

 tification of the species. 



The leaves of ferns are called fronds, the part corresponding 

 to the stem being called the stipe and the rest the lamina or 

 blade. It will be noticed that they differ from other leaves in two 

 important particulars. First, they are not folded or plaited when 

 young, but are rolled up like a watch-spring (Fig. 5), and develop 

 by unrolling and expanding. Second, the veins fork. In the 

 higher plants, a few strong veins give off smaller ones at irregular 

 intervals, but in the ferns the first veins divide into two equal 

 branches, and when these divide again it is always into two equal 

 divisions. (Fig. 4). 



There are other additional characters that serve to distinguish 

 the ferns from other nearly related groups, or from one another, 

 but the above are all that need be taken into consideration now. 

 When one finds a plant whose leaves have forked veins, bear 

 spores, and are rolled up in the bud, he may be sure he has a fern. 

 With the exception of the cinnamon ferns ( Osmunda ) and the 

 Christmas fern ( Dry opt er is acrostichoides), the ferns of the 

 Northern States do not fruit before midsummer. In the next paper 

 something will be said about where to find and how to identify 

 our common species. — IV. N. C. 



