52 
NOTES ON SOME PLANTS OF WESTERN 
QUEENSLAND 
By S. L. EVEREST 
The climate of Western Queensland is characterised 
by short periods of heavy rainfall alternating with longer 
periods without effective rain or with irregularly 
distributed light rain. Rainy periods are neither con- 
sistent nor reliable and plants must be adapted to 
survive in soils subject to violent fluctuation in moisture 
content. One of the most common structural adapta- 
tions to this environment is the development of dual 
root systems. There are many examples, but four plants 
will serve to illustrate the nature of this adaptation. 
Curly Mitchell Grass ( Astrebla lappacea), l’soralea 
cinerea and Glycine falcata all grow in pedocalcic clays 
derived from Cretaceous calcareous sandstones. Some of 
these soils are in situ with the parent rock below them 
at various depths and some have been developed on 
material deposited by the rivers on their broad, flat 
flood plains. Surface soils vary somewhat in colour and 
texture, but the profile follows the same general pattern. 
From surface to 6 or 9 inches there is a layer of loose 
friable soil, crumbly when dry, very sticky when wet. 
Below that, usually to a depth of 30 to 36 inches, there 
is a zone of massive clay. When dry this is hard and 
cracks into large, irregular blocks, the cracks often being 
two inches or more wide. Below the massive zone is a 
transition zone where the soil becomes yellowish in colour 
and more friable. This gradually gives place to a 
yellowish-brown friable clay which does not develop 
wide cracks on drying, but breaks up into shallow 
polygonal plates. 
In such soils. Astrebla lappacea forms tussocks com- 
posed of numerous culms, erect or obliquely ascending 
from an intricate system of short scaly rhizomes. The 
culms themselves are hard and finely fluted and the 
leaves stiff. At ground level, the tussocks range in 
diameter from about 1 inch to more than 6 inches. Even 
where Ashebla is the dominant species, it rarely occupies 
more than 4 per cent. of. the total surface area, though 
