76 
PRACTICAL COURSE IN BOTANY 
examples of plant parasites, though the latter is only partially 
parasitic, as it merely takes up the sap from the host and 
Fie. 88. — Beech root: A, grown in 
unsterilized wood humus: 7, strands of 
fungal hyphe, associated at a, with 
humus; B, grown in wood humus freed 
from fungus by sterilization—it is not 
provided with fungal hyphz, and has 
root hairs, h. (A and B both several 
times magnified.) 
manufactures its own food 
by means of its green leaves. 
86. Saprophytes. — Akin 
to parasites are saprophytes, 
which liveon dead and decay- 
ing vegetable matter. They 
are only partially parasitic 
and do not bear the haustoria 
of true parasites. Many of 
them, of which the Indian 
pipe (Monotropa) and coral 
root are familiar examples, 
obtain their nourishment in 
part, at least, by association with certain saprophytic fungi, 
which enmesh their roots in a growth of threadlike fibers 
that take the place of root hairs and absorb organic food 
from the rich humus in 
which these plants grow. 
Such growths are called 
mycorrhiza, meaning 
“fungal roots.”” Similar 
associations are formed 
by some of the higher 
plants also. The root- 
lets of the common beech 
and of certain of the 
pine family, for instance, 
are often enveloped in 
a network of fungus fi- 
bers, and in this case root 
hairs are developed very 
poorly, or not at all. 
Fie. 89,— An air plant (Téllandsia), growing 
on the underside of a bough. 
Besides greatly increasing the absorbent 
surface by their ramification through the soil, the mycorrhizal 
threads may possibly benefit the plant in other ways also, as, 
