(1978) who found a close relationship between the canopy 
radiance and the functioning bio-mass. 
The Araucaria angustifolia 
The canopy of Araucaria when plotted from aerial 
photography using a CPI stereoplotter reveals its very 
"lumpy" nature, in which brightly illuminated masses of 
leaves are separated by intensively shallowed arsas. The 
characteristic candelabra effect produced by a canopy and 
its shadow are shown in Diagram 1. 
The leaves, which persist for many years, are spirally 
arranged, and may develop a basal twist which tends to 
present the broad face to the light. They are lance 
shaped, leathery and sharp pointed. Their size depends on 
their position. There are marked differences in leaf 
colour because of age; young leaves show two effects, the 
margins are light in colour, equal to 151 A or B on the 
Royal Horticultural Society Colour Scale, while the 
remainder of the leaf is a yellowish green, code 145 B/ 
144 B on the R.H.S. Scale. The old leaves are much darker 
in colour and it is uniform over the whole leaf with a 
colour code of 137 A or B. 
Diagram 2 shous a general cross section of a leaf, with 
alternate resin and vascular bundles, a marked palisade 
cell layer and a tightly packed mesophyll, Diagram 3 is 
an enlarged section, drawing attention particularly to 
the lignified cell layers on both sides of the cross 
section, the thick cuticle, and the unvacuolated mesophyll, 
Collins (1978) has pointed out that the older a plant 
becomes, the longer are the wavelengths that are absorbed. 
The crown structure, with extensive areas of branches and