STRUCTURE. II 
STRUCTURE. 
What is a Fern? The vegetable kingdom is divided 
into two great classes, Phenogamia (flowering plants) and 
Cryptogamia (flowerless plants). The ferns belong to the 
latter class. The Royal Fern (Osmunda regalis) is often 
called the Flowering Fern; but this is a misnomer, as no 
ferns produce true flowers. The fruit, or rather fertiliz- 
ing organs of the fern, are peculiarly situated, and have a 
very showy appearance, especially when fully developed; 
whence the name of Flowering Fern. 
A fern can be easily distinguished from all other plants 
by the texture of the foliage, by the peculiar character of 
the veins, and more especially by the position of the fertil- 
izing organs. On the under side.of the leaf are situated a 
number of dark brown spots, some on the edge of the leaf, 
some at the center, and others scattered irregularly over 
the surface. These are the organs of fructification, and 
are common to all ferns. There are a few exceptions, 
however, in the manner of the arrangement of the fruit- 
spots. The Sensitive Fern (Ozoclea sensibilis) furnishes a 
very good example of this exceptional method. ‘Toward 
the end of summer it sends up from the root a spike re- 
sembling that of a flowering plant in fruit. (Plate XL.) 
This spike of fruit-like bodies is technically called the 
fertile frond, while the other, which is green and leaf-like, 
is termed the sterile frond. The fertile frond, or leaf, of 
most ferns is more contracted than the sterile, and the 
morphological law governing the conversion of leafy tissue 
