KOOTS 
107 
food supplies. 
Therefore, pro- 
cesses are devel- 
oped which pene- 
trate and absorb. 
The mistletoe and 
dodder are seed- 
plants which have 
this habit, and 
both have such 
processes (see Figs. 
102, 103). This 
habit is much more 
extensively devel- 
oped, however, in 
a low group of 
plants known as 
the fungi. Many 
of these parasitic 
fungi live upon 
plants and animals, 
common illustrations being the mildews of lilac leaves and 
many other plants, the rust of wheat, the smut of corn, etc. 
70. Root structure, 
In the lowest groups 
of plants (algae, fungi, 
and moss-plants) true 
roots are not formed, 
but very simple struc- 
tures, generally hair- 
like (see Fig. 104). In 
fern-plants and seed- 
plants, however, the 
root is a complex 
structure, so different 
from the root-like pro- 
Fio. 103. A section showing the living connection 
between dodder and a golden rod upon which it is 
growing. The penetrating and absorbing organ (h) 
has passed through the cortex (c), the vascular 
zone (6), and is disorganizing the pith (p). 
FIG. 104. Section through the thallus of a liver- 
wort (Marchantia), showing the hair-like pro- 
cesses (rhizoids) which come from the under 
surface and act as roots in gripping and ab- 
sorbing. In the epidermis of the upper surface 
a chimney-like opening is seen, leading into 
a chamber containing cells with chloroplasts. 
