STRUCTURE. 13 
view I have prepared a plate, with several diagrams, giving 
most of the terms used in description. See Plate I. 
The Root (Plate I, figure 1), represents an under- 
ground stem or rhizoma of the common bracken (/%eris 
aquilina), after Sachs, showing the remnants of the old 
and decayed, as well as the young and living leaves. It 
is a very characteristic root-stock. An examination of the 
plates will enable the reader to recognize the different 
kinds of roots, a general description of which is given 
by Moore: “The proper roots of ferns are fibrous, and 
they proceed from the under side of the stem, which 
assumes a creeping mode of growth; but when the stem is 
erect they are produced toward its lower end on all sides 
indifferently, and proceed from among the bases of the de- 
cayed leaves. ‘The stem of a fern forms either an upright 
stalk, called a caudex, which in our species seldom elevates 
itself above the surface of the ground, but in certain exotic 
ferns reaches from thirty to fifty feet or more in height, 
_ and gives a tree-like character to the species; or it extends 
horizontally either on or beneath the surface of the soil, 
and forms what is called a rhizome or creeping stem.’”* 
The Leaf. (Plate IV.) The lower portion of the leaf 
is termed the stipe, and is somewhat analogous to the leaf- 
stalk of flowering plants. The upper part is more properly 
termed the frond, and is the fruit-bearing portion. The stipe 
may be simply a continuation of the root-stock (Plate I, fig- 
ure 1), or it may be jointed (articulated), as shown in Poly- 
podium (Plate IV). This is an important character in the 
classification of ferns. Leaves are either simple or com- 
pound. They are simple when undivided; compound when 
cut or parted into segments or lobes. Nearly all of the 
ferns have compound leaves. 
* Popular History of British Ferns, page 12, 
