August, 1941 
The Queensland Naturalist 
121 
War Savings Certificates 
.. £40 
0 
0 
Bank Balance 
. . 15 
8 
6 
Total 
. . £55 
8 
6 includes 
Nature Lovers’ League A/c. . . 
.. 38 
19 
10 
Tent A/c 
. . 5 
6 
8 
E. N. MARKS, Hon. Treasurer. 
C. W. HOLLAND, Hon. Auditor. 
MYCORHIZAS 
By H. E. Young, M.Sc. 
Most people, including many biologists, think of the 
absorbing roots of trees in terms of agricultural plants in 
sand culture, i.e., with root tips and root caps and 
numerous root hairs for absorption purposes attached to 
the sides of the roots. This is, however, not even remotely 
the case in the majority of trees and in many other plants. 
In the woodlands roots are invaded by fungi. In 
many trees the invaded roots become modified so as to lack 
root haii*s and possess no direct contact with the soil. They 
become deeply imbedded in a compact fungal tissue called 
the mantle which surrounds them until their death. 
The simple process of absorption of soil moisture and 
nutrients by root hairs is replaced by a complex system of 
nutrient exchange between two widely different members 
of the plant kingdom — a fungus and a tree. To reach the 
conduction tissue of the higher plant the water and nutri- 
ents must be absorbed by the fungal threads or hyphae, 
which branch out in the soil, and pass back along them 
through the bark-like mantle of fungus, and finallv 
through or around several layers of cortical cells which 
are separated from one another by a continuous network 
of fungal hyphae called the “Hartig net.” This arrange- 
ment provides a more extensive and efficient absorptive 
system than the root hair one, which indeed frequently 
does not exist in nature. 
Such a structure is regarded neither as a root nor a 
fungus. It is a combination of both producing a distinct 
organ. It is called a mycorhiza — a compound Greek term 
meaning a fungus root. In 1900 Stahl designated the pro- 
cess of plant nutrition involving mycorhizas as mycotrophv 
or fungus nutrition. 
