DIMORPHIC FOLIAGE OF ACACIA RUBIDA, Lai 
species as Acacia rubida, A. longifolia, A. floribunda, A. 
linifolia, A. elongata, A. juniperina, A.vestita, A.hispidula, 
A. Cunninghamii, A. faleata and A. melanoxylon. Prob- 
ably some trace of this ancestral foliage is to be found on 
all Acacia seedlings, but as an evidence that the process 
of evolution is still in progress there is the fact that not 
only is there a wide range of leaf-form among various 
species, but also is there variation in the persistence of 
the bipinnate leaves on seedlings of the same species. 
A seedling of Acacia melanoxylon recently raised, ceased 
to produce bipinnate leaves after it had reached a height 
of about three inches while other seedlings of this species 
from sheltered situations at Mount Wilson, have been 
known to reach five feet before showing any phyllodia. 
One of the most interesting Acacias which furnish 
examples of dimorphic foliage is A. rubida, A. Cunn., though 
Bentham makes no allusion to the bipinnate leaves when 
referring to this species, and was probably not aware of 
their existence.* 
This plant grows on siliceous rather than basic formations 
preferring a fairly cool climate, and extends along the 
mountain region throughout New South Wales, and slightly 
into the adjoining States, flourishing in damp spots on the 
moist rather than on the dry side of the mountains. 
SEEDLING OF A. rubida. 
Hypocotyl at first curved, later erect, terete, 7 mm. - 
above the soil, 1 mm. thick. 
Cotyledons sessile, oblong, about 7 mm. long and 3°5 mm. 
broad, of a red colour on both sides, glabrous. 
The pinnate leaf, which springs with a short stalk, from 
the same level as, and about midway between the cotyle- 
dons, has up to five pairs of leaflets, each leaflet being much 
* B. FI, Vol. 11, p. 366. 
