46 
The South Australian Naturalist 
too. that deseits arc places of extraordinaiy interest and beautyj 
and that they may become of great economic importance. Klls- 
\\oith Huntington, possibly the greatest comparative geographer 
living, IS a declared lover ot deserts — of tlieir scenery, their plants 
and their peoples. Professor Osborn tells us that, if we define an 
and climate as one with 10 inches of rain per annum, or less, then 
about 37 per cent, of the whole of Australia is arid; 1,105 452 
sc|uaie ipiles out of a total area of 2,974,581 square miles. In the 
State of South Australia five-sixths of the area has 10 inches or 
less of ram per annum, 3I A000 square miles of arid land out of a 
totaj of 380,000 square miles. 1 herefore, he argues, South AuS' 
tiahan botanists are well situated for a special study of the flora 
of arid lands. 
Some lev' years ago on the opening of the Transcontinental 
line from Port Augusta to Kalgoorlie, it was my pleasure to make 
that most interesting journey. Naturally, like other travellers, 1 
w'as desirous of finding out as much as possible of the natural 
history of the country passed through. As we journeyed through 
the low, but beautiful and varied vegetation that characterises the 
country from I arcoola to Ooldea, 1 questioned all and sundry 
as to the exact significance of the term “mulga.” The history 
is too long to tell, but there was much humour in it. I finally 
came across a gentleman wdio had lived 50 years in the mulga 
countn - I tried again and again to pin him down to one plant or 
shrub as being mulga, but he never could get to the window in 
time to see the plant I was pointing out. When w^e got to know 
one anothei better (and this does happen on the long journey 
of the east-wmst line) he became more confidential, and wdth an 
embracing sweep of his arm over the visible countryside, he said: 
"\\'e call tile wdiole lot of it mulga.” What my friend really recog- 
nised, from the shcepgraxing point of view, was what Professor 
Osborn would call the “mulga plant community:” this includes 
all the suite of plants that lives and flourishes under the same 
conditions as mulga. The real mulga of the botanist is a definite 
shrublike wattle (Acacia aneura). 
Some years ago it w^as my privilege to wander througli the 
bush with Professor Osborn himself; he then told me that" when 
he first came to^ Australia the plant character that continually 
iorced itself on his notice was the w'ay in which almost all Austra- 
lian plants have adopted devices, such as leaf shape, leaf arrange- 
ment, &c., so as to obtain as little sunlight as possible. The char- 
acteristic leaf arrangement in English plants is just the reverse; 
it is designed to obtain as much sunlight as possible. A couple 
of years ago, when driving through the Blue Mountains in the 
