36 
The Queensland Naturalist June, 1939 
which has the really efficient adaptation to inclemency 
of climate. The decisive battles between species or be- 
tween plants and their sub-aerial environment are often 
fought beneath the surface of the soil. 
If we could view the subterranean landscape we 
would find it as richly varied as that of the surface — 
tangled masses of shallow roots, deeply penetrating tap- 
roots, gnarled subterranean creeping stems, dormant 
bulbs, corms and tubers, and a teeming population of 
scavengers, parasites and stray visitors. The soil 
seethes with life; it is a dynamic system changing from 
hour to hour, from season to season, and from year to 
year. 
The size of subterranean parts of plants is often sur- 
prising. The Western Australian Christmas Tree is about 
20 feet in height, but what are apparently trees are 
really branches of a subterranean trunk, sometimes 
hundreds of yards in length ; it is actually a giant 
amongst trees, but being underground it is not noticed. 
Even the common pumpkin may have several miles of 
roots. Sorghum is a plant which has a smaller leaf sur- 
face than maize, but area for area its leaves transpire 
more water. Measurement has shown that it lias a much 
larger number of fine roots to supply the leaves. Herein 
lies one explanation of the greater transpiring power of 
many xerophytic plants; their above-ground parts are 
the organs which get rid of water, but their root systems 
supply it. 
The normal functions of roots are to obtain water 
and inorganic salts from the soil, and to act as anchor- 
ing organs ; but in many cases they either fortuitously 
or habitually assume extra duties. Natural grafting be- 
tween roots of the same individual is the rule in the 
strangling figs or banyans, whose roots anastomose to 
form a trunk; but it is also commonly observed in up- 
rooted trees of other species. There is much more oppor- 
tunity for this fusion in the soil than there is between 
branches, where the union may be disturbed by wind. 
In the individual, root grafting probably has no value, 
but when the root systems of adjacent plants become 
fused at a sufficient number of points, the transfer of 
food material from one to another may be of great im- 
portance. A case is on record where, after a Eucalypt 
was cut down, the stump healed over and continued to 
live without leaves. (This happened in the Gladstone 
district, and was recorded in the proceedings of the 
