6 HOW TO KNOW THE FERNS 



barren leaves. The stem does not start at once 

 to produce leaves bearing the sporangia or spore 

 cases. Thus, in the very young Fern the fronds 

 are always barren ; as the stem becomes older, 

 fertile fronds are produced. In some cases the 

 sporangia are borne on distinct leaves, as in the 

 case of the Hard Fern, or on special parts of the 

 leaves, in the manner to be seen in the Royal 

 Fern. The difference in such cases is not really 

 a very important distinction. A careful ex- 

 amination of the fertile portion of a Royal Fern 

 frond will show a small amount of green tissue, 

 or mesophyll, as it is called, at the lower portion 

 of the pinnae. Actually the fertile leaf, or part 

 of a leaf, is similar to the barren portions, save 

 that it produces a much reduced amount of 

 green tissue or, in some cases, perhaps none at 

 all. 



In general appearance the Club Mosses bear a 

 resemblance to the true Mosses, and hence the 

 popular name, which is certainly rather mis- 

 leading. With these plants the leaves are 

 small and almost bristle-like, and are gathered 

 closely round the stem. In many of the Club 

 Mosses a large part of the stem lies closely 

 along the ground, and from this at intervals 

 roots are sent down into the soil and leafy 

 shoots rise upwards. The sporangia are pro- 

 duced on special leaves, which are usually 

 gathered together in the form of cones. 



Although they vary somewhat in size, all 

 the Horsetails are striking plants. Here there is 

 a branching underground rhizome from which 

 arise the aerial stems. The most distinctive 

 feature of the plant are the whorls of smaller 

 branches which arise from the joints of the 

 main stem. These carry on the work which is 

 usually assigned to the foliage of the average 



