152 



STRUCTURE AND LIFE HISTORIES 



142. Two Kinds of Fern-leaves. Careful examination 

 of the leaves of some mature ferns will disclose the fact 

 that they are not all alike. Some of them are merely 

 foliage-leaves, and do not differ in any essential point from 



FIG. in. Osmunda Claytoniana. Young sporophylls, showing circinate 

 " vernation. Note the spore-bearing pinnae. 



the foliage-leaves of higher plants, such as the maple or 

 lily; they possess stomata (Fig. no), and also resemble 

 the leaves of higher plants in their internal structure. 

 All fern-leaves, however, have a very characteristic ar- 

 rangement in the embryonic or bud condition, being 



