Betts. — Aut ecology of Plants, of Peridofife Belt, Nelson. 287 



Anatomy. 



Leaf (figs. 13-17). — The general shape of the leaf in transverse section 

 is shown in fig. 13. From this it will be seen that the midrib is very 

 prominent, that the tomentum is thick, and that the leaves are revolute 

 almost to the margin. 



Fig. 14 illustrates a section 'passing through the midrib. Both the lower 

 and the upper epidermis consist of regular squarish cells which do not 

 contain chlorophyll and which have their cell-walls very much thickened. 

 There are no stomata in this region. From the epidermal layers very 

 numerous fine hairs are produced, which form a silvery tomentum below 

 the midrib and over the whole of the upper surface of the leaf. There is 

 a thin cuticle on both surfaces of the leaf. 



The vascular system in the midrib consists of one large bundle and 

 two much smaller ones. The vessels of the xylem are arranged in very 

 regular rows separated by xylem parenchyma. There is also a fairly large 

 amount of parenchyma in the phloem. Above the phloem and below the 

 xylem there is a mass of stereome, consisting of cells with very thick 

 walls and small cavities. The cells above the xylem are larger than those 

 below the phloem. 



Fig. 13. — Celmisia lonqifolia var. gracilenta. Transverse section of leaf (x 36). 



a, tomentum ; b, vascular bundle. 



Just above the lower epidermis there are 2 rows of chlorenchymatous 

 cells. These cells are roundish, and have their walls slightly thickened, 

 and contain numerous chloroplasts. Just below the main bundle these 

 cells have their walls much thicker and contain a much smaller number 

 of chloroplasts. 



All the space between the upper epidermis and the chlorenchyma of 

 the lower surface (except that occupied by the vascular bundles) is filled 

 by a tissue consisting of very large cells with fairly thin walls. These cells 

 are arranged very closely together, so that there are only minute intercellular 

 air-spaces where three cells meet. All these cells form an aqueous tissue. 



Section of the Leaf through the Lamina (fig. 15). — The upper epidermis 

 consists of regular more or less squarish cells which are larger than the 

 epidermal cells above the midrib. They have their walls considerably 

 thickened, the external walls being thickened the most, and there is a 



