THE STEM. 45 
(Fungi,) Lichens, and all the other lower orders of plants, ex- 
cept the Ferns and one or two others, make up this class, the 
leading character of which is to consist of cellular tissue 
alone. The Ferns and Club-mosses (Filices and Lycopo- 
diacew) have usually been included in this class from many 
points of resemblance, particularly the absence of sexual or- 
gans : but they possess a distinct vascular tissue, and have 
spiral vessels. They appear to occupy a middle ground be- 
tween cellular and vascular plants. 
140. Cellular stems are sometimes termed AcRocGENous, 
from their manner of growth, the new matter. being added 
at the point or extremity, or by the bases of the leaves unit- 
ing. They are called Cellular by some, Acotyledonous by 
others, and Linnzus applied to them the term Cryptogamic, 
signifying flowerless. 
. 
I VASCULAR STEMS. 
+ L ENDOGENOUS STEMS. 
141. These consist of bundles of vessels irregularly dis- 
persed through cellular tissue, and covered by a thin cuticle. 
The sugar-cane (Saccharum officinarum), the Lily, the Palm, 
and the Iris, have this kind of structure, the cellular and vas- 
cular tissues being blended together through the entire sub- 
stance of the stem. A transverse section of the common 
Cane affords a good illustration of this class. See also Fron- 
tispiece, Fig. 1. 
