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 
