Water in Trees under Australian Conditions . 
93 
The total number of leaves was 3,323 with a total area of 7*665 
sq. metres. The leaves, being almost all vertical, had stomata on both 
surfaces and the water absorbed per hour per sq. metre of transpiring 
surface was therefore 2*22 c.c. A cut branch in air, however, lost 68*5 c.c. 
per sq. metre per hour, and on examination of the cut stem of the tree 
it was found that a gummy mass beneath the bark had been carried by the 
axe over the cut surface, blocking very many of the vessels. 
In a similar three-hour experiment with a young tree of Eucalyptus 
viminatis 4-6 metres high at 23-24° C. it was found that the eosin rose 
93 cm. per hour, and 108*6 c.c. were absorbed, which was only 3-84 c.c. 
per hour per sq. metre of surface, whereas a cut branch with 805 leaves lost 
70-15 c.c. per sq. metre during the first hour of the experiment, and another 
with 880 leaves lost 60-9 c.c. of water per sq. metre per hour during the 
latter two hours. In this case the blocking was due to the notching of the 
axe edge and imperfect trimming, but it suffices to show that partial 
blocking at the cut surface affects the amount absorbed much more than 
it does the maximal rate of ascent and never causes the latter to become 
higher than it would be in the intact tree. 
In addition, the amount absorbed by a cut tree, as well as that exhaled 
by a cut branch suspended in air, steadily decreases, even if the external 
conditions remain constant, or even if they change so as to favour trans¬ 
piration. Thus in a two-hour experiment with a cut branch of Eucalyptits 
viminatis , while the temperature rose from 23° to 26° C., the amount of 
water transpired per sq. metre was 40-8 c.c. in the first half-hour, 30 c.c. 
in the second, 27 c.c. in the third, and 23*5 c.c. in the fourth. 
Taking every possible precaution, the following data were obtained 
in November, 1908, between 11 and 2 p.m. with two young trees of 
E. viminatis (A and B) and one of E. amygdalina (C):— 
Height of tree 
Temperature 
Rate of ascent 
No. of leaves 
Total transpiring surface 
Water absorbed per sq. 
metre of total leaf surface 
Water transpired per sq. 
metre from a cut branch 
suspended in air 
None of the observations exceeded half an hour’s duration, but even 
then the rate of absorption is much less than the maximal transpiration 
values for rooted plants of Eucalyptus corynocatyx (300-400 c.c. per hour 
per sq. metre of transpiring surface). It is evident, therefore, that the 
sap may rise in Eucalyptus trees 1 at rates of 30 or 40 feet an hour under 
1 Vertical leaves, stomata on both surfaces. 
Eucalyptus viminatis. Eucalyptus amygdalina . 
A. 
4-3 metres 
26° C. 
12-3 metres per hour 
7,460 
23-11 sq. metres 
116-6 c.c. per hour 
80-95 c.c. per hour 
B. 
3-95 metres 
27 0 C. 
10-33 metres per hour 
6,200 
20-92 sq. metres 
146-8 c.c. per hour 
118-3 c.c. per hour 
C. 
5- t metres 
26° C. 
6- 5 metres per hour 
3,520 
28-8 sq. metres? 
202 c.c. per hour 
113-6 c.c. per hour 
