APPLICATION OF PHYTOSOCIOLOGICAL TECHNIQUES 297 



to a class for aphyllous species (not present in the Mucambo plot but occur- 

 ring elsewhere in rain-forest vegetation in such plants as the epiphytic cactus, 

 Rhipsalis), Raunkiaer established six leaf-size classes: leptophyll, up to 25 

 sq. mm.; nanophyll, with an upper limit of 9 X 25 sq. mm.; microphyll, 

 9- X 25 sq. mm.; mesophyll, 9^ X 25 sq. mm.; macrophyll, 9"* X 25 sq. 

 mm.; and megaphyll, larger than the latter class. Figure 3 shows the distri- 

 bution of the Mucambo species in these leaf-size classes. We also have distri- 

 buted the leaves through a series of arithmetic classes, increasing by 25 sq. 

 cm. units. Similar data were prepared for 150 tree species of the Castanhal 

 rain-forest sample plot. On the basis of the Raunkiaerian leaf-size classes, 

 which have a logarithmic base, the distribution is symmetrical about the 

 modal mesophyll leaf-size class (table 13). When the distribution is made 



Table 13. Frequency of species in Raunkiaerian leaf-size classes, terra firme rain 



forest, Para 



Mucambo Castanhal 



Class Number Per cent Number Per cent 



Aphyllous 



Leptophyll 



Nanophyll 



Microphyll 



Mesophyll 



Macrophyll 



Megaphyll 



Total 



according to arithmetic classes, it is strongly skewed. It is completely un- 

 known whether such a distribution of leaf sizes is abnormal for the world 

 vegetation, as there is no "normal" distribution comparable with Raunkiaer's 

 normal life-form spectrum, but it is undoubtedly characteristic of equatorial 

 rain forest (table 14). 



Further analysis of the leaves of trees available from the Castanhal study 

 shows that 69.3 per cent are simple, 24.7 per cent are once-pinnate, l.i per 

 cent are bi- or tri-pinnate, and 2.6 per cent are palmate divided or deeply 

 lobed. At Mucambo we found 71.2 per cent to be simple, 18.7 per cent pin- 

 nate, 6.5 per cent bi- or tri-pinnate, and 3.6 per cent palmate. Also at Mu- 

 cambo we found the proportion of compound leaves to increase with the 

 height of the trees: megaphanerophytes were ii.i per cent compound, meso- 

 phanerophytes were 21.0 per cent compound, and nanophanerophytes were 

 16.7 per cent compound. Microphanerophytes were too few in number for 

 the percentage to be meaningful. Although the leaflets of compound leaves 



