136 R. H. CAMBAGE. 
DIMORPHIO FOLIAGE OF ACACIA RUBIDA, AND 
FRUCTIFICATION DURING BIPINNATE STAGE. 
By R. H. CAMBAGE, F.L.S. 
With Plate I. 
[Read before the Royal Society of N. 8S. Wales, June 3, 1914.] 
AUSTRALIA is the home of the phyllodineous Acacia, that 
form of Wattle which, as an adaptation to environment, 
has gradually dispensed with its ancestral type of pinnate 
leaves, and developed a flattened leaf-stalk or phyllode to 
carry on the functions of ordinary leaves. A few of this 
class are also found in New Caledonia, the Indian Archi- 
pelago, and the Pacific Islands.’ 
In a large genus like that of Acacia, there are naturally | 
many stages of transition to be met with in this process of 
evolution, from those forms which wholly retain the bipin- 
nate leaves on the adult trees, to those which never show 
them after the plants are a few inches high. 
A common sequence of seedling leaves with a number 
of Acacias, is that immediately after the cotyledons, there 
comes one simply-pinnate leaf, and after that, a varying 
number of alternate abruptly bipinnate leaves appear, the 
common petioles being mere stalks on the lower leaves, 
but gradually becoming more dilated on the upper ones, 
until at last they develop without any bipinnate leaves on 
their tips, and now, as phyllodia of various widths, carry 
on the functions of leaves. 
In addition to those mentioned by Lubbock? this is also 
the usual sequence with, amongst others, such typical 
1 BP, Vola, piso. 
* See Sir John Lubbock, ‘“;A Contribution to our Knowledge of Seed- 
lings,” Vol. 1, p. 399, (1892). 
LL 
