June, 1939 The Queensland Naturalist 
35 
others would perish, and they are undoubtedly of prime 
importance. They should not, however, be made the 
basis of the argument that all peculiarities of growth or 
structure are of equal value, or even of any special value 
at all in adapting the plant to its environment. Dr. 
Cuthbert Hall, for example, considered that the chemical 
composition of the essential oils of the Eucalypts of the 
highlands in southern New South Wales had enabled 
them to climb the mountains after the Kosciusko uplift. 
Eucalyptus oils are end-products, and have passed out 
of circulation in the plant’s metabolism, so that it is 
extremely unlikely that they could have any such func- 
tion. Perhaps this is an extreme example. There are 
many others, however, which at first sight seem very 
reasonable until they are examined experimentally. 
Plants which are capable of enduring a prolonged 
drought without injury — the xerophytes — have many 
special anatomical characters, such as toughness and 
leatheriness of leaves, hairiness, and so on. These are 
often explained as adaptations for the reduction of 
transpiration. Yet it has been shown that many plants 
with these peculiarities of structure are able to give off 
water at as rapid a rate as other plants, and in some 
cases more rapidly. A Russian plant physiologist, Kus- 
min, found such xerophytes as Alhagi camelorum and 
Medicago coerulea remained green in the desert near Baku, 
on the Caspian Sea, when all other plants had dried up ; 
but that these plants had a transpiration intensity twice 
that of the ordinary sunflower. There is a discrepancy 
between leaf anatomy and foliar transpiring pow T er which 
has led such workers as Shreve, Pool, and others to con- 
sider that the one does not account for the other. A slow 
transpiration is certainly found in cacti, which are fleshy 
and have a very greatly reduced surface, and in 
Xanthorrhoea, in which the stomata are very deeply 
sunken ; but in general the transpiring power of xero- 
phytes is not obviously bound up with their supposed 
adaptive leaf structure. 
Above-ground parts, however, are only portion of a 
plant, and in considering the adaptations to any par- 
ticular habit, the subterranean parts should be considered 
in equal detail. It must be remembered that many 
plants die down to the ground every year, but carry on 
to the next season by dormant or relatively dormant 
underground organs — bulbs, tubers, rhizomes, and such 
structures. In such plants it is the subterranean part 
