184 Transactions. 



Leaf-anatomy. — The epidermis has little or no cuticle. It gives off a 

 few unicellular trichomes, especially above the midrib. It consists of two 

 layers of cells on the upper surface, except above the midrib, and both are 

 without chlorophyll, and contain oil-drops. The cells of the outer layer 

 are very wavy in outline as seen from surface view. Stomata are present 

 only on the lower surface, where they are numerous, and are on a level 

 with the other epidermal cells. They are not provided with special auxiliary 

 ■cells. 



The palisade layer is two or three cells deep, the third often consisting 

 of rounded cells. It contains abundant chlorophyll, and measures about 

 one-third the whole thickness of the leaf. The spongy parenchyma contains 

 a large amount of air-space, and in the mature leaf is devoid of chlorophyll, 

 giving the latter a silvery appearance on the under-surface. 



Large cavities, with thin or no special bounding walls, occur at fairly 

 regular intervals in the palisade layer. Bundles of raphides of calcium 

 oxalate are abundant in the spongy parenchyma of the midrib. 



The vascular bundle of the midrib is surrounded by large parenchyma 

 cells, many of which contain mucilage, while raphides are found in a few. 

 Anthocyan may occur in the epidermis above the midrib. 



The raphides are probably a waste product, stored in the leaves, and got 

 rid of when the leaf falls. Since the leaves are not on the tree when it is 

 exposed to cold dry winds, at a time when root-activity is not so great, this 

 may possibly be the reason why they have not developed a thick cuticle 

 to protect against excessive transpiration. The leaf -anatomy of Fuchsia 

 excorticata has several points in common with that of Plagianthus betulinus, 



the other deciduous tree on the Port Hills. 

 Both have crystals of calcium oxalate in 

 the mesophyll of the leaves, those of the 

 latter being similar to the crystals in the 

 leaf of Parsonsia. The cuticle of Plagi- 

 anthus is also rather thin, and in its pali- 

 sade layer are cavities or large empty cells, 

 very similar to those of the Fuchsia leaf. 

 Both leaves contain abundance of muci- 

 lage when the leaf is ready to fall, and 

 also in Plagianthus when it is quite young. 

 The occurrence of mucilage in Plagi- 

 anthus is probably a character of system- 

 Fig. 5.-Lower epidermis of leaf atic importance however, and is not 

 of Fuchsia excorticate ; x 250. specially produced owing to the deciduous 



habit, as it is common in the family 

 Malvaceae, according to Solereder.* Crystals also are common in most 

 of the members of the two families Onagraceae and Malvaceae. No 

 mention is made by Solereder of the cavities in the palisade layer of 

 the leaves of these two species. (See figs. 4 and 5.) 



Olearia Forsteri Hook. f. 



This is a small tree, occurring only in the bush. It has a stringy bark. 

 The leaves are leathery, and have a thick tomentum on the lower surface. 



* Solereder, H. : " Systematic Anatomy of the Dicotyledons." Translated by L. A. 

 Boodle and F. E. Fritsch, vol. 1, p. 14t>. 



