
CHAPTER II. 
VEGETATIVE ORGANS OF FERNS. 
Acrogenous growth—The Roors—Their nature and position—Buttress-like masses of 
roots in Tree Ferns.—The SrEx—Caudex— Rhizome— Their peculiar modes of 
growth— Accretion—Internal structure—The tissues— Vascular system and vena- 
tion—The Fronps or Leaves—Not true leaves— Their diversity— V ernation— 
Peculiarities of structure—The stipes—The lamina—Different modes of division 
—Venation—Its peculiarities—Application of terms : costa, veins, venules, vein- 
lets—Arrangement of veins— Venation as a generic feature, 

Tur Ferns, as already stated, belong to the class of Flowerless 
plants, and consequently their vegetative organs make up nearly 
the whole bulk of the plants. They have, in all cases, a very 
distinct stem which, however, assumes several different characters, 
as will be hereafter explained ; and they are furnished below with 
roots, or food absorbing organs, and above with leaves of a peculiar 
character, to which the name of fronds is given. 
The group of plants to which the Ferns belong is called Acro- 
genous; this term being applied to it because the increase in size 
which takes place as the plants grow, is effected by means of accre- 
tion at the apex or growing-point. The several organs of the F'erns 
are readily distinguishable from each other, by which character 
they are known from certain other plants of low organisation— 
the Thallogens, in which the stems and leaves are blended. The 
vegetative organs of Ferns are the following, namely, the Root, 
the Stem, and the Frond or Leaf. 
The Roots of these plants are always fibrous, and in their younger 
portions are clothed with fibrils, or fine soft hair-like bodies, which 
give them a velvety or downy surface. When the stem assumes the 

