TWO PINNATE LEAF BORONIAS AND THEIR ESSENTIAL OILS. 203 



of this iii Hooker's description of B. Gimnii, or are any 

 serrations shewn in his figure. In B. Gunnii also the leaves 

 are " more crowded, but the lowest pair always distant 

 from the stem" than B. pinnata (Bentham, PI. Aus., vol. l) y 

 but in B. thujona the leaves are certainly not more crowded 

 nor are the lowest pair always "distant" in comparison 

 with B. pinnata, rather the reverse. 



The young plants resemble B. floribunda in appearance, 

 and in the size and colour of the flowers, and in the field 

 would be much more readily taken for that species than 

 for B. pinnata, B. floribunda, however, is readily dis- 

 tinguished by the large globular stigma and the absence of 

 the strong smelling oil in the leaves and buds. 



Anatomical Characters of the Leaf. 



In transverse section the leaf is found to be particularly 

 thin, (Plate XIV, fig. 3) averaging about 0'20 mm. in thick- 

 ness. The palisade mesophyll is usually confined to one 

 layer. Intercellular spaces are very prominent in the 

 palisade tissue as seen in the left of figure (3), where the 

 leaf is cut somewhat obliquely by an almost horizontal 

 section so as to pass through both the palisade and spongy 

 tissues. Intercellular spaces are also particularly notice- 

 able in the transverse section. The lower epidermis has 

 decidedly sinuate lateral walls, which are occasionally pitted. 

 The cuticle in both cases is thin. The upper epidermis is 

 composed of much larger cells, which are not sinuate, the 

 lateral walls also possessing simple pits. Stomata are 

 usually confined to the lower epidermis, and average about 

 300 per square millimetre, with an average size of 0*03 mm. 

 by 0*025 mm. They are rarely found on the upper surface. 



The oil glands are directed towards either side, and are 

 usually from 0*1 - 0*15 mm. in diameter. The four epidermal 

 cells forming the cover for the gland are much thinner than 

 elsewhere, and are sunk slightly below the surface. This 



