276 
INTRODUCTION TO BOTANY 
chlorophyll-containing tissues in such a position that they 
may receive light; at the same time, through the fibrovascu- 
lar bundles of the leafstock and the rhizome, soil water and 
Fie. 215. Types of fern leaflets 
A, bracken fern; B, shield fern; (, 
spleenwort; D, the maidenhair fern. In 
the different specimens the sporangia 
are ats, the indusium at 7, and the false 
indusium at f.i 
substances in solution may be 
transported to the chlorophyll 
tissue. The root system an- 
chors the plant in the earth 
and absorbs the water needed 
in food manufacture. 
In general, plants that rise 
above the soil and into the air 
must be supported and must 
secure water from some source. 
The climbing vines which are 
dependent upon other plants 
are supported chiefly by these 
other plants. Most vines pro- 
cure their supply of water 
from the soil and transport it 
by means of their own vascular 
tissue. Fibrovascular tissue, 
by reason of its strength, 
makes possible the upright 
position and is essential (as 
is also the absorbing and an- 
choring root system) alike to 
the fields of upright grain and 
to the forests. The importance 
of vascular tissue in ferns 
and higher plants can hardly 
be over-estimated. 
261. Types of ferns. Ferns are usually distinguished from 
one another by the leaves, the sori, and the sporangia. There 
is much variation in position and arrangement of sori in dif- 
ferent ferns (fig. 215). In some the sori are dots placed regu- 
larly upon the leaf. In others they are like slits or blistery 
