12 FERNS ' OF KENTUCKY. 
into fruit is here well exhibited. (See Plates L, LI, and 
LIL) 
Another characteristic feature of true ferns is presented 
in the unfolding of the leaf. In its youngest state it is 
curled up in a circinate fashion; and, as it comes up slowly 
through the leaf-mold, it gradually unfolds its scroll-like 
form until it reaches its last delicate leaflet, and soon 
. afterward assumes an appearance the most graceful and 
beautiful in the vegetable kingdom. ‘The Adder’s Tongue 
Fern (Plate LIX), and the Moonwort Fern (Plate LVII), 
are exceptions to this rule; but, to say the least, they hold 
a doubtful place among the true ferns. 
The frond, or leaf of a fern, differs from that of flower- 
ing plants in this—the latter performs only a foliage office, 
having no connection with the fruit-bearing organs, while 
the former bears the organs of fructification, exercising, at 
the same time, the functions of the leaf. However, the 
terms are almost synonymous, and in our discussion of the 
subject we may use the term leaf as well as frond. Prof. 
Sachs, one of the greatest living authorities on vegetable 
physiology, seldom uses the term frond. 
The arrangement of the veins of the leaf, as has already 
been mentioned, is very different from that of ordinary 
plants. Having their origin at the mid-rib of the leaf or 
leaflet, they proceed by successive bifurcations toward the 
margin. By decolorizing a plant in a solution of chloride 
of soda, this peculiar structure of the leaf, as well as the 
arrangement of the fruit-spots, will readily appear. 
Various terms are used in describing ferns, which it will 
be necessary to explain. A clear comprehension of these 
will enable the student to understand the written descrip- 
tions at once, and to determine the exact relations of any 
fern without the aid of an illustration. With this end in 
