152 Transactions. 



The cortex consists of large oval cells with thick walls. The outer 

 region of the cortex is very compact, but the inner part has the cells loosely 

 arranged. 



The phloem is of the usual type. The xylem is composed of numerous 

 vessels of moderately large diameter, and of wood-fibres with thick cell- 

 walls. 



The medullary rays are iiumerous and are uniseriate ; the cells have 

 their walls thickened and lignified. .\11 the medvillary-ray cells contain 

 tannin. 



The pith is composed of two kinds of cells : (1) Small more or less 

 ]}olygonal cells with thick walls, and containing tannin ; (2) much larger 

 thin-walled cells : in these the walls are only slightly lignified and the 

 cells do not contain tannin. 



22. Dracophyllum Urvilleanum A. Rich. 



Growth-form. — A much-branched shrub 3-5 ft. high ; the branches are 

 slender and erect, with black or dark-brown bark. The leaves are erect, 

 .slender, 1-3| in. long. The sheathing base is \-\ in. broad, brown, striate, 

 and membranous ; the blade is very narrow and coriaceous. 



Anatomy. 

 Leaj (figs. 17, 18). — The upper epidermis consists of small roundish cells 

 with thickened slightly lignified walls. A thick cuticle is present. Some 

 of the epidermal cells are produced into short stil? unicellular hairs, which 

 have extremely thick cutinized walls. The lower epidermis consists of 

 slightly smaller cells than does the upper : these cells also have thickened 

 lignified walls ; and there is a thick cuticle. Stomates are found on both 

 surfaces, but they are much more numerous on the lower surface. The 

 guard-cells have thickened walls, and the opening is protected by guard- 

 cell ridges. 



Fig. 17. — Dracophyllum Urvilleanum. Transverse section of leaf ( X 48). 

 a, cuticle ; b, stereome ; c, vascular bundle. 



The chlorenchyma is homogeneous ; it is a very compact tissue composed 

 of large cells with tlieir walls slightly thickened. Oil and tannin are present 

 in many of the mesophyll cells. 



There are 7-9 vascular bundles ; all the xylem elements are lignified, 

 and the phloem parenchyma cells contain tannin. 



Surrounding each vascular bundle there is a large mass of stereome ; 

 3-5 of these bands of sclerenchyma extend right across the leaf, from one 

 epidermis to the other. The groups around the bundles nearer the margins 

 of the leaf are much smaller. The sclerenchymatous cells are 4-6-sided, 

 and are very compactly arranged. The cells have very thick walls and 

 minute lumen. 



In the margins of the leaf there are 1-3 layers of larger sclerenchymatous 

 cells. 



