268 



Transactions. 



The cortex consists of fairly large, thin -walled cells ; in an old root, as 

 illustrated, the hairs of the piliferous layer have disappeared, and the sub- 

 dermal layer of cortical cells have their walls slightly suberized. 



4. Brachycome Sinclairii Hook. f. 



The appearance of a single rosette is given in fig. 24. The plant is more 

 or less succulent, 1-3 in. high, and practically glabrous. The plant has a 

 short, thick, branching rhizome, and it is by this means that the plant is 



Fig. 24. — Brachycome Sinclairii. Entire plant (x IJ). 



able to form mats. The leaves are J-2 in. long, broad and rounded at the 

 tip, and gradually narrowed into the flat petiole ; they are deeply toothed, 

 and in some cases appear even pinnatifid. 



Anatomy. 



Leaf (figs. 25-27). — In transverse section the cells of the upper epidermis 

 are seen to be large and somewhat squarish, with all their walls thickened, 

 the outer ones considerably, the thickening being equal to about half the 

 depth of the cell-cavity. The stomata, which are numerous, are raised 

 above the cavity of the epidermal cells, but are at the same level as the 

 thickened external walls. The guard-cells have thickened walls and guard - 

 cell ridges. In surface view (fig. 26) the cells of the upper epidermis are 

 seen to be large and irregular or polygonal. A thin, unevenly but not 

 deeply ridged cuticle is present. On the upper surface there are about 

 220 stomata per square millimetre. 



The cells of the lower epidermis (fig. 27) are similar to those of the 

 upper, except that the cell-walls are not so much thickened ; in surface 

 view these cells are more irregular in outline than the cells of the upper 

 epidermis. Stomata are not as abundant as on the upper surface ; there 

 are 150 per square millimetre. The guard-cells of the stomata of the lower 

 surface are a little smaller than in the upper surface. 



The chlorenchyma is difierentiated ; the palisade tissue occupies about 

 one-third and the spongy parenchyma two-thirds of the mesophyll. In 

 both the cell-walls are very thin. The palisadic cells are oval or oblong 

 in transverse section, about twice as deep as wide, fairly compactly arranged, 

 and containing numerous small rounded chloroplasts. The spongy tissue 

 consists of large, more or less rounded cells, with small air-spaces between 

 the cells ; they contain a much smaller number of chloroplasts than the 

 palisade-cells, and form an aqueous tissue. 



